by Ken Goodman, LCSW
Fear of vomiting emetophobia

If you have a fear of vomiting, just reading the title of this article might make you a bit queasy. The mere mention of the "V word" might send you into a state of anxiety. If you can relate, I encourage you to press on despite your worry, so you can take the first steps to overcoming it.


No one enjoys vomiting and everyone thinks it’s disgusting, but most people are not afraid of it. But if you suffer with this type of phobia (specifically known as emetophobia), you are not only repulsed by the idea of vomiting, you fear it. Many people say that the anticipation of vomiting is often worse than the act itself.

And because you don’t know when it will happen, you are constantly on guard, rearranging your life to ward off any possibility of puking.

What Causes Nausea?

Stomach discomfort and nausea can be caused by motion sickness, a stomach bug, food poisoning, excessive eating or drinking, food intolerance and…anxiety!

That’s right. Anxiety and worry can cause stomach discomfort and nausea. And if you don't vomit when you’re anxious…you won’t!

Treatment Works

Treating vomit phobia is best accomplished through cognitive-behavioral therapy (CBT) and exposure and response prevention (ERP). Treatment involves correcting faulty beliefs, reducing avoidance, and confronting challenging situations step-by-step. You are given tools, a new perspective, a winning mindset, and a strategy for facing your fears. Your motivation for ending your suffering is important because the therapy does take time, hard work, and courage. You must have self-discipline and determination to win. And if you do…you can beat emetophobia!

Also by Ken Goodman:

Additional Resources:

About the Author


Ken Goodman, LCSW, treats anxiety and OCD in Los Angeles.  He is the author of The Anxiety Solution Series, a step-by-step audio program, and Break Free from Anxiety, a coloring, self-help book for anxiety sufferers. Ken Goodman is an ADAA Clinical Fellow. Visit his website. 


Now available- Ken Goodman hosts an ADAA webinar on "Overcoming the Fear of Vomiting." Watch the video on ADAA's YouTube channel.


    I struggle with the same exact problem. I have two boys (3 and 4) and every month it’s something. Germs in general scare me but especially any type of stomach related illness. My husband handles it but sometimes he is not home and it is up to me. I feel terrible bc I can’t be loving and hold them bc of my fear. This phobia controls my whole life. I am constantly cleaning and sanitizing and worrying. I pick them up from school earlier on my bad days bc I don’t want them around more germs. I don’t eat or drink what I want to bc I’m terrified of getting sick. When the kids bring home a stomach virus I take anti nausea pills and drink water/Gatorade and literally only eat crackers for 3 weeks. I try to avoid places with more kids (more germs). I hate eating out and forget drinking. My husband wants to get a boat and I’m terrified of feeling motion sick but I don’t want to miss out on the fun. This phobia is consuming and horrible. I’ve struggled with it my whole life and literally I haven’t thrown up since I was 6 (I am 32 now). But it is worse now that I have young kids. I want to overcome this fear but it seems impossible.

    Being here on this website and researching answers is the very best "nudge" in the right direction.

    For me, the following has changed my life in the emetephobia regard:

    * breathing exercises (google "deep breathing for anxiety" or something similar. Practice when you feel good and then put the breathing exercise to work at the first sign of anxiety.

    * Drink ginger tea. At the first sign of anxiety, I brew a cup of ginger, and bring in the breathing technique. (I like the brand "traditional medicinals" for their excellent quality in teas)

    * Don't hide your fears; talking with others is healing.

    * Yoga; take a class, watch a youtube video, etc. Helps build courage, mental and physical strength, great place to practice conscious (and not frantic) breathing. Begin your yoga session by taking a moment to ask for whatever it is that you need to be your highest best self, and then keep this request in mind as you do your practice. At the end, give thanks to the universe (or who or whatever you believe in) for taking the time to "meet you" for your practice. I do yoga first thing in the morning, before tea, before bills, before phone calls, before even talking with my family about anything too serious (other than "Good morning.") It really helps set the day up with positiveness, and especially hope and courage.

    * Lastly, it may help to seek professional help, like an Ayurvedic practitioner, a yogi, or a therapist that specializes in this particular anxiety.

    I wish you the very best.
    Love & Light

    I totally agree. I’m supposed to be going off to college this year. But I can’t help to think that I’m not going to have my mom there when I start to feel sick. I confined in her to help me. Most of the time she gets really angry Becasue she doesn’t understand it. And I understand that. But sometimes I just need someone who understands.

    I deal with this too and completely understand and I also know how great it is to talk to someone who understands so if you or anyone else wants to talk and maybe help each other my snap chat is skyemonique1 ❤️ Good luck

    OMG, this is my problem. I have such a fear of getting sick I’ll wash and wash my hands till the dry and sore, When I’m in bed at night I have nightmares of me not feeling well. I even hate the word that starts with a V. I know sounds dramatic and a little crazy. But once I start thinking about having anxiety that’s when everything starts. The only thing that helps me is talking to my boyfriend and always having ginger ale and mints. I’m glad I’m not the only one who has this.

    What you just explained is exactly what happens to me and I understand what your going through 100%. Recently I got better because I didn't pay attention to it anymore, I didn't let myself be afraid because there is nothing to be afraid of. I started eating normally again like eating without stopping myself because of being afraid of having a tummy ache at night. I used to starve myself at night because I thought it was better then throwing up, the truth is you won't throw up, it's the nerves and thoughts in your mind that believe you to think these negative thoughts.

    Flying long distances was a big problem for me, still is, after reading some positive ways to help with this phobia I realized that facing the problem is easier then ignoring it. So that is what I do now, I do the things that make me feel anxious and realize in that moment that it's always going to be okay and things get better. You just have to believe in yourself and in the people around you.

    You are never alone, have faith in yourself and others and you will be okay.

    I'm 20 and I wanna say around the time I was about to turn 19 is when I started feeling like this. I've had this fear for a while but it's intensified. I used to be able to drink and have fun but now my anxiety gets in the way and I start to feel sick giving me more anxiety. I just found out this is a phobia and honestly I am crying right now because all this time I thought I was weird for it.

    I’ve had this phobia ever since I was about 11..for about half a year I would not eat anything at school or anywhere else-not even in my own home because I was constantly worrying “What if this food makes me sick?”
    This ‘eating disorder’ only made me sicker and weak as time went on and I was wasting my childhood away. Although I do eat regularly now, I still have panic episodes and I will sometimes reject food when I go to restaurant. I feel like I’m alone when I have these panic attacks...I feel like no one understands my fears. It usually gets worse at night..I always think to myself “what if I throw up when I’m sleeping..and then it will be a mess..and..” it just gets out of hand..
    Thank you for your’s very nice to know that someone else understands how I feel..

    Hello, see I started to cry when I read your comment, I know exactly what that feels like I mean I’m awake at 4 in the morning, scared..praying cause that’s really all I can do to hopefully make me feel better..sometimes I think to myself “how am I gonna keep going like this..I’m just a teenager”
    Honestly I wanna be like other people who throw up and just get over it real quick..I wish I could be like them..I’ve gone to therapy when I was younger cause I’ve been dealing with this for years and it’s’s torture
    I had to pretend I was getting better just so I can stop going to my therapist..when I would go I felt like I was crazy or something
    I’m just so tired of living like this..

    I feel the same way I can't go to school don't have friends anymore because of it I can't do anything thing without the consent worry of getting sick my life had Been over taken by anxiety

    I am literally the same way. It's so bad for me too and I'm glad I'm not alone. I'm going on a medication soon that side effect is nausea and I'm so worried about it. I'm literally just like you though and Idk what to do

    I feel exactley the same way its the worst thing ever.. I have it every single day every day of my life it limits my life and I guess thats what hurts me the most I don't get to go out and see my friends or get on the train to see my family further away because I'm just so scared of the feeling sick and what if I then have to vomitt and its just awful like I feel like its going to be like this forever I don't see a future anymore because it finishes me off so much.. i find tea helps me allot peppermint, kamille, or ginger! anything herbal really but these three are the best.. It also helps to talk about things that bothers you in life.. and have a good cry it seems stupid but if you feel sick from anxiety then having a good cry and talking about it helps allot.. and go out for walks get your head free take a person you feel really trusted with with you.. sit in the open air somewhere it really helps to just think about things and you should feel better I hope you feel better soon and never forget your not alone It will get better for you best wishes

    I have the same problem somewhat every night I go to bed I have the thought of "am I going to get sick throughout the night " in fact I'm lying in bed right now with these thoughts plus my stomach feels wierd like I'm hungry or something

    Oh man... I feel for you so much. I have the exact same thing happening to me, it has got so much worse in the last year. I have to sleep by a bin and like you go to sleep every night terrified I'll have to wake up and get ill... it really really sucks... I'm also a teenager and I'm afraid to go out or drink or eat to much ot go on rides or do literally anything that could make you I'lland I feel like its stealing my life. The year gives me horrible panic attacks that jsut make me feel ill and make everythig worse... It's sucks. So so much. I hope that you've found some way to deal with it and feel better in yourself. X it's really tough x here if you want to talk x

    I feel exactly the same I have panic attacks and start to shake and freak out why am I like this it happened to me when I was 12 and then it stopped throughout the age of 13 and now I’m 14 and it’s started again... please I just want to get rid of it I shake all night and can’t sleep because I’m so so scared that I’m just gonna wake up and throw up and I don’t know what to do! Please will anyone help me I’m scared I think I need a therapist

    I couldn't relate more. I am 16F and currently in therapy and taking medication to help me as my phobia is effecting me so much. I have my GCSE's starting tomorrow and I haven't been in school for a while so I'm terrified to go. I understand your message was sent a couple of months ago, and wondered if you have any tips on how your dealing with it. I feel like its taking over my life and I can't see a future ahead of me right now.

    I too have this fear. It's so debilitating and i also have post natal depression. I cinstantly feel scared and unhappy and i cry alot. Some days i fear dying and being nothing. I just want to feel good. Why is it so hard?

    i get scared to go on school camps and to go to the toilet at school. I get worried when i wake up in the night because someone is in the toilet because i always think they are going to vomit. my heart races and i just freak out. how can i fix this?

    I hope since it’s been a few months your better with this now, and if you are I hope I didn’t just bring it all back up for you. Truth is, I know exactly how you feel, yours sounds more intense than mine I still leave my house but I force it a lot, my advice is to get educated on how sickness travels, once I did that I pretty much became a little ocd but I’m okay living with ocd over constant fear. It does ruin your life, I stopped eating meat cause of the fear, I never ate out, I was/am always aware of how every single person in the room with me is feeling, I watch people I sense for weird sickly behaviours, I ask a million questions. It’s terrible. I always wonder who I could be if I didn’t have this, inthis of all the possibilities I could do and have if I wasn’t held back by this. Sometimes I ever turn away from people I love if their sick, it’s disheartening, and it kills you. Makes you feel weak, like if something that stupid would make you stay away from someone you loved than maybe you don’t deserve them at all to begin with. But you do deserve them and you deserve happiness in what form that may be for you. You deserve love and kindness and forgiveness. You have to forgive yourself because this doesn’t define you. You are not your mental illness. You are not your anxiety. You deserve so much more than that. The best way I get myself through it is I tell myself how fast time goes, how I’ll feel better in the morning, how everything will be okay and work it’s self out. Sometimes I get so mad at myself for being so scared I end up looking like such a idiot in front of people I work with or friends and family because I will panic and have an attack if I’m faced with it. I wish I was stronger and truthfully I have no idea why we are so contained by this fear, I wish we were free. So much easier said than done though, so ,much easier. It’s hard talking to people who don’t understand what you feel or think. Having to tell someone from the beginning every time is exhausting, it’s lonley really. Anxiety, depression, ocd, fears in general... it’s lonely. And I hope you can find a way out of the darkness and into the light. You will survive this and everything that comes your way. My best advice is to go to your local doctor and get him to write you a referral for a counselor or a pycholoigist and talk with them, having a referral means it’ll be free and you can find one online you like and feels best fits what you need. And to be honest no one should have to go through this alone. Not you, not me.. no one. Sometimes having someone to tell all your dark and inner thoughts to, helps a lot. You’ll be surprised what you can achieve when the wait of the world lifts off your shoulders. You’re not alone. Not even for a minute. Live on friend.

    I grew up a normal child. I had no fears. I loved life. I grew up in South Florida. I use to play in the canals and ponds and never had a issue. When I moved to the Florida Panhandle I didnt think anything about it and played in a ditch. Well the next day I woke up vomiting. I was sick for literally two weeks. I would get sick several times a day. Little did I know my life was changed forever. After that I developed a fear of vomiting. I became OCD to the extreme. It controlled my life. It ruined my life. Every minute of every day I constantly think about it. Its been 20 years now living with it. Coping. I am scared to eat out. Avoid sick people like the plague. I go into a lockdown and freeze up around sick people even if its a cold because I fear it could be more. I get tunnel vision and forget the World around me. The only thing I think of is my fear. The darkest thing greater than death it seems. It manipulates every decision. Every thought. I try to remind myself when I feel any stomach pain its not the end of the World. That it will get better. Tomorrows another day. But tomorrows also another day to worry.

    Agh I know exactly how you feel! I am the same way, although I’m in highschool I still stay up so many hours the time I should be in bed because I’m scared of getting sick, like I don’t know how to deal with it if I’m alone!

    my emetophobia all started when my sister got the stomach bug really bad in kindergarten. i remember being so scared i isolated myself and washed my hands so many times. since then i've only gotten the stomach bug three times and i haven't gotten sick in 2 years. middle school has been so hard for me. i have ibs which causes me constant stomach pain, which does not help my fear at all, ive missed sooo many days of school from this phobia, ive changed my diet so many times, and ive had to cancel so many plans with friends and family. it really does suck. it has made my life so so so miserable at times, but its also taught me so much. im so glad im not alone and i hope one day everyone can get over there fear!!! stay strong everyone!

    I relate to you so much ! I get scared of seeing other get sick and me as well. I also I have ibs too and I missed so many events and school too due to this. Glad to hear that someone is in the same situation like me. We can get through it !

    Thanks for sharing this, it’s nice to see people going through the same as I am. I thought all this time I was just being ‘pathetic’ or ‘stupid’ but knowing that it happens to others, well, it seems to make a little more sense in my head now.

    For as long as I can remember I’ve been terrified of anything resembling vomit or feeling sick. When I was younger, I would literally shake and cry as soon as any feeling of sick come on. As well as if anyone else mentioned they felt nauseous.

    I’m now 20 and unfortunately it’s still there. I tend to just secluded myself from others when I feel sick. Sometimes I drive out in my car for hours and not come back until I feel totally fine again. It’s gotten a lot worse over the past few weeks, to the point where I can’t eat out of the house anymore. The fear is unbearable some days and gets me down. So trust me when I say that if you’re feeling this too, you’re not alone. It’s such an awful sensation that can last for hours. I know I should seek help but I feel embarrassed to tell a doctor as I think they won’t take it seriously.

    Reading these thread of comments has allowed me too show myself it’s not just myself in suffer, I have had the exact same issues for 2 years now. It all started when I finished High school and It would stop me from eating, getting out of bed or even simply playing with my dog, one time i starved for 3 days under the scarce thought I was going to be sick during the night, I suffered bad insomnia and lost 20lbs in a week, baring in mind at that time I was only 150lbs. I had to take anti Sickness tablets for a week to just get my appetite back, I took a sleeping tablet whilst under no food for 3 days and slept for a further two days without waking up, finally my mum realised something was wrong and I was taken to the hospital and given a Ultrasound... waste of everyone’s time answering baring in mind I’m a male it was kinda funny at that point, baring in mind this problem had persisted for 6 months by now I was always under the impression dying would be a better option than going through the problems.
    Never the less, I thought I had a breakthrough with blood tests, they called me In and nothing was there, they automically came under the assumption it was GERD, A lactic acid issue.. i knew it wasn’t the case I had acid build up due to smoking, This all came to a sudden stop instantly when I met my girlfriend but 3 months later it was back with a vengeance and it was all due to the stress she had me on, I’m unable to leave my house without the feeling of sickness, I can’t leave my house for anything, I refuse to get back into college under the scarce I might get Ill, I stopped working because one day I felt so sick I almost threw up on a gas pipe, which worriedly me more and I had to tell me boss I couldn’t work again due to breaking a disc in my spine, it’s been almost a hear since I’ve worked, I want to get back so bad but I can’t get myself round to finding a new job, it scares the hell out of me.. I can’t go for a shower without feeling like I’m gonna throw up, I can’t eat a single meal either, can’t take my dog for a walk, can’t even go out and see my friends and I feel this is all mental but my mum or anyone’s else for that fact doesn’t want to know about it, or they just laugh. So thank you to anyone who took time reading this, and if you can give me a help in hand I’ll be forever grateful. Thank you all for sharing this as it’s hard to admit what seems such a minor issue. Good luck to everyone

    i am the EXACT WAY this is crazy. thank you for this. atleast i knoe theres someone out there like me. it sucks. so bad. but what can ya do, it ruins EVERYTHING.

    Wow, I have the same exact problem, the slightest feel of nausea and my anxiety kicks off. I can't sleep as I'm constantly in fear and I have trouble doing my school work as I just cannot stop thinking about it.

    I think my phobia stems from having celiacs disease. I’ve always hated vomiting (like everyone else), however I never got sick as much as I do now that I’ve been diagnosed with celiacs. Something as simple as cross contamination can make me vomit hours later. I’ve canceled trips because I’ve been so worried about getting sick. I get panic attacks when I think I’m getting sick. Im at my breaking point and I’m not sure what to do.

    I am the same exact way! I am 20 years old and I’ve been like that since around 5 years old. I got diagonosed with extreme anxiety and in my doctors notes she put “irrational fear of vomit” in high school I was out an entire semester because this guy in my class had the stomach virus and I was terrified to get it and had a panic attack in my forth period. I can’t even hear the words throw up, vomit, etc. At night like you said I’m terrified I’ll wake up in the middle of the night and get sick, I have panic attacks and panic attacks make you nauseus so I just freak out even more. I keep peppermint oil with me all the time because it’s supposed to ease upset stomachs. I can’t stay at peoples houses, I can’t eat certain things because I’m terrified I’ll get sick. I’m almost 21 and I’ve never been drunk because I’m scared I’ll get sick. There’s so much I miss/have missed out on due to this fear.

    I feel the exact same way.. it’s actually happening to me right now. It’s 4 am, and all i’m doing is worrying timid i’m going to throw up. And when i worry about that, it’s triggers my anxiety and then i actually start to feel sick.

    I have had vomit phobia my whole life, its very frustrating because it does effect my everyday life. It’s come to the point where I even get terrified in the day as well as the night. Usually if someone mentions they feel sick that will stick to my mind for a few days and cause me To panic. On the worst of nights, where I am the most anxious, I will uncontrollably shake, I am too scared to cry. Even when I see that my friends on my story have thrown up I become terrified and overthink. I have to make excuses for why they have thrown up to make me feel better. It is SO frustrating because I don’t even want to stay at my university in case I feel ill and it is such a long journey. Once my friend woke up in the night and threw up and I ran from the room, the room smelled so bad even though she said she didn’t smell anything and I slept in the spare room shaking trying to calm myself, and I asked my dad to pick me up( this was about 3 in the morning) and I didn’t even see the vomit. I wish I could’ve comforted her but my instinct was to get out of there so I could be away from that vomit. I can’t tell anybody about it because they don’t understand, and they just say ‘if you vomit that’s ok’ . I can’t accept that I’m too scared. Add my snapchat or insta if you have the same problem, snapchat - aaliyahhhhhx Instagram- a_scriv

    I've had this phobia ever since I was little.
    Whenever my stomach feels slightly unsettled I start to worry, even if it's only indigestion or the fact that I feel hungry. I have ear buds in right now as my brother is vomiting in the next room and the sound of it makes me worry that I'm going to be sick myself. Even things such as a dry mouth or needing to cough sometimes can trigger this fear.
    I stop myself from doing a lot of things as a teenager because of it. I steer well away from alcohol because I'm scared it will make me sick.
    I hope that this fear is something that I can overcome.
    Throwing up isn't nice; but it's not worth the panic and anxiety - if it happens, it happens and then it's over. That's what I have to try and remind myself.

    I don’t remember being afraid of it when I was younger. I was never afraid of myself being sick but I remember I’d always have to hold my ears when someone was. Obviously I don’t do that now but if I’m exposed to that I get chills running all up and down my body. Over the past, I’d say 6 years, it’s started to grow into a fear that I feel could start affecting my life soon if I don’t get a hold of it. I get really anxious any time my family or friends tell me they feel nauseous or might be sick, any time I get nauseous it takes me so long to relax because I’m thinking “what if I’m sick, I can’t be sick.” But I liked something I read on here that basically said “people remember the anxiety leading up to being sick more than the actual being sick” and it’s kind of true. No one around me has this fear and any time I try to explain it they say “no one likes it, grow up.” They don’t understand it’s a real fear of mine such as their fears of confined spaces or heights or death. But anyway it’s nice to know I’m not the only one who feels this way.

    I know your pain. I'm the same way. I have no control of it and it's runing my life and my relationships with friends and my boyfriend. I've tried to use several calming techniques and nothing seems to work. I want to feel better but I can't. And the thought of even going to the doctors makes me sick.

    This is exactly how I feel and it really gets me down sometimes because I’m 18 and it stops me from being fun and going out Incase I’m ill. Sometimes I think if I change the bin in my room then I’m tempting fate and it will make me be sick or as soon as I go into a restaurant I look for the toilets immediately just Incase but it never happens. I just want to be a normal teenager and not be so boring because I’m so scared of being sick and not go out or do fun things. I’m about to start uni next month and I don’t want to be held back anymore.

    SAME HERE. I have the exact same fears and precautionary steps as you do. I’m in a constant state of worry because of the fear of being sick. I worked at a daycare and I caught the stomach bug 3 times in 1 year, which sparked my fear of throwing up and stomach bugs. If my stomach even starts to feel like it does when I’m about to throw up, I have a panic attack and stop everything. Most of the time, I’m just making it a lot worse. I also developed a severe fear of getting sickness of any kind, since I also was sick very often when I worked with kids. It consumes my life daily, and I worry constantly. I’m only 20 but i can’t live like a normal 20 year old because of anxiety and constant worry. I avoid people who say they feel nauseous or sick, or I have a panic attack if they stay around me too long. It’s just a mess. I’m working on counseling and positive thoughts for the time being. You’re not alone, my friend.

    Ok I just read your comment and it’s strange how similar we are?I went out to a party last night, I’m a teenager, and I hardly drank anything in fear of throwing up. But last night when I came home I was shaking and just doing what I usually do. Convincing myself I was about to be sick. So I called my girlfriend and she distracted me even though it was horrible for her to see me like that. I’ve woke up this morning feeling exactly the same but I’m having my hair dyed at the hairdressers in a few hours and I don’t want to go in the car because what if I’m sick? If I was going to be sick surely I would have been sick already?? Right??

    I just want it to go away too i’m so young and i just hate being so scared all the time of being sick. i don’t avoid eating, but i am always nervous whenever i’m dizzy or bloated or nauseous. it tears me apart i just want to be normal!!!!!!!

    Hello I feel the exact same way. I'm constantly worried about being sick. It's starting to control my life. I cant eat, drink, sleep, or even go out in public without being worried now. And it's so bad. I feel so down because of it and it lay awake at night just miserable because I'm so tired of it. Hopefully one day we can both find help to get over this fear.

    I have had this fear my whole life ,now I have two small children my nightmare is this time of year , both my kids have been sick today and I’m struggling to cope with life knowing I’ll probably get it , people find it funny but I would rather die than be sick, it really is ruining my life, I’ve tried everything and nothing helps , wish it didn’t bother me

    I have the same feeling at night as I stay up crying and crying I also have the same thing about going out non stop asking myself what if I’m sick what if I’m sick I didn’t eat for 7 weeks because of this and went to the doctor but they couldn’t help and they said it’s mental not physical. I stress about going out places thinking what if someone is sick there. I always scare myself with everything like this and I ant to get over it but it’s the worst thing in the world I stayed up till 5:00 am this morning with no sleep due to feeling nauseous and scared. I hate this!!!

    When i was really little, I didn’t mid sick very much, but I hadn’t a best friend who hadn’t emetophobia and it rubbernecked off on me a bit but not too badly. Now though, I am 14 and (usually when I don’t be get enough sleep) recently I’ve been feeling sick all the time and I’m conatantly stressing that I will have to run out of the classroom and be sick in the corridor and it’s starting to affect my life...

    I feel the EXACT same way. I'm 21 almost 22 with a 2 year old daughter who just threw up 3 hours ago and ever since I've been extremely nauseous just at the thought of me getting sick.. and before she through up I was just fine. Ever since senior year in high school though which was 3 years ago I've been getting anxiety almost every single night and I get very nauseous. Never throw up. I think I've thrown up from it like 2 or 3 times out of the 3 years of having anxiety but I'm currently trying to distract myself cause I'm currently extremely nauseous