Sneezing your way to a big belly: Do allergy medications make you fat?


Some folks have seasonal allergies.

But if you’re like me, battling your allergies is a year-round affair.

Some days are certainly better than others, but overall, I have been a chronic user of anti-histamines since my teens. Cleratin, Reactine, Aerius, and Life Brand versions thereof have all at one point or another helped me breathe.

So you may imagine my concern when I came across a recent paper published in the journal Obesity discussing a possible link between the use of anti-histamines and body weight.

During a graduate course in neuro-endocrinology I took a couple of years ago, I learned about numerous central signals than control energy balance.

Histamine was not one of those.

Apparently, histamine is a neurotransmitter which, in addition to mediating the inflammatory response, and thus symptoms of allergies, is known to suppress appetite.

Thus, antihistamines, which work by blocking the H1 histamine receptor, may remove this appetite suppressing signal. Indeed, the authors of the current study point out that increased appetite and weight gain is a reported side-effect of antihistamines. (I just checked the packaging of my antihistamines and there was no mention of increased appetite or weight gain.)

To investigate this link, Ratliff and colleagues used data from the National Health and Nutrition Examination Survey during the 2005-2006 years.

“268 adults (174 females and 94 males) reported use of an H1 antihistamine and completed all outcome measure components. 599 age- and gender-matched controls (401 females and 198 males) were used as a comparison for body measurements, plasma glucose, insulin concentrations, and lipid levels.”

What did they find?

“After adjusting for gender, prescription H1 antihistamine users had significantly higher weight (P < 0.001), BMI (P < 0.001), waist circumference (P < 0.001), and insulin levels (P < 0.005) compared to healthy controls.”

Specifically, controlling for age and gender, those who take anti-histamines were 55% more likely to be overweight than their non-allergy-suffering peers.

However, the increased risk of overweight with antihistamine use was more pronounced for men than women (70% vs 21% increased likelihood).

No differences between the groups were observed for any of the other metabolic risk factors studied.

Of course, this is only a correlative study, and countless other confounding factors may be playing a role. Nevertheless, the preliminary observation is intriguing.

I have tried to think back to times when I take antihistamines and recount whether I had an increased appetite, and I’m not sure my personal experiences corroborate this observation.

Thus, for the sake of proper breathing, I’ll stick to my anti-histamines for the time-being.

I wonder if any of our readers have noted a change in appetite when taking antihistamines.


Ratliff, J., Barber, J., Palmese, L., Reutenauer, E., & Tek, C. (2010). Association of Prescription H1 Antihistamine Use With Obesity: Results From the National Health and Nutrition Examination Survey Obesity, 18 (12), 2398-2400 DOI: 10.1038/oby.2010.176

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30 Responses to Sneezing your way to a big belly: Do allergy medications make you fat?

  1. alice says:

    Yeah, for years. Often wondered if there was research on it/ if it was just me.

    • Fascinating! I wonder why I never noticed it myself. Maybe I’m such a chronic user of anti-histamines, I’m used to the enhanced appetite.

      How quickly do you notice the appetite increase and how long does it last?

      • alice says:

        From what I can tell/ remember it’s more that if I’m taking them regularly I notice I’m more likely to want to eat between meals. I suppose I notice it more in the mid-morning and would usually take a pill around 8ish. To be honest, I can’t remember that strongly though – I only need them in the Spring, and tried to avoid taking them this year.

  2. Liz says:

    Fascinating! I’ve been using antihistamines year-round for about 15 years, so I can’t remember whether my appetite was different before. I do have a big appetite – although in my case it’s not so much that I eat large meals, but that I start feeling hungry again an hour or two after eating. I take other medications, too, though, so I don’t know whether I can blame the antihistamines.

    Like you, I don’t think I could stop taking antihistamines and still function well. But if more research bears this out, it might push me to try skipping the pills occasionally.

  3. Rowan says:

    I’ve seen Mirtazapine, an anti-depressant, described as a central nervous system anti-histamine; weight gain is a well-known side effect. A package insert I have – not necessarily the most recent available – states that ‘increase in appetite and weight gain’ is a ‘common’ side effect that occurs in ‘1 in 10 to 1 in 100 users’.

  4. Lyn says:

    Mighn’t people who take anti-histamines have poorer health in general? Or at least be less inclined to go outside and exercise because of allergens?

    • kaiee says:

      Not all allergens are outside, and for you to say people with allergies are pretty much lazy and have poorer health is just plain out RUDE I have severe allergies to everything inside and outside and I still exercise at least 3 hours a day you dont have to leave yourhouse to excersice. I was on reactine for 3 years & I gained 50 lbs, I have a very strick diet & excerside DAILY & still cant get the weight off. I’ve been off them for a week now and have lost 10 lbs. For everyone else, my doctor recommended a nasal spray (avamys) because my symptoms are mostly sinus’s. & it works just great. And as for people like you, dont judge people because of the obsticles they have in there life if they want to be healthy they will find a way to do it it may be harder to go outside and excercise when you have allergies but we make it work, doesnt mean we just sit back and say oh well ill just be fat cauase im allergic, people like you are whats wrong with teh world.

  5. Angel says:

    Was activity level controled for? Just wondering as when I’m having breathing problems I exercise less because it’s so unpleasent. I’ve been using allergy and asthma meds for about 45 of my 50 years and that is the effect I notice the most.

  6. Ellie says:

    The histamine-blocker effect (as in Remeron) is much of why I assume I see weight gain with several of the antidepressants and some of the antipsychotics. Other receptors, too, but this one is fairly well established. There had been some speculation a while ago that perhaps the appetite increase seen with olanzapine and clozapine could be blocked with use of H2 blockers (famotidine, etc., although, unsurprisingly, Lilly pumped use of its own H2 blocker…) Haven’t followed up on that.

    Similarly, it’s why we use lower doses of Remeron to stimulate appetite – deliberately – because of the histamine effect. At higher doses, the drug has more 5HT and NE effect, and is less prone to making one want to eat two pizzas…

    • k says:

      I miss mirtazapine. It worked well both as a sedative and as an antihistamine for me. I was never able to avoid weight gain, although I was on a high dose. Alas, other SNRIs (nefazodone, duloxetine, and venlafaxine) don’t have the same sedative benefit as mirtazapine.
      Trazodone and many of the old tricyclic antidepressants seem to have similar effects on histamine and weight gain as mirtazapine, which might be why Prozac and successors were widely accepted (in relative terms).

      Most “sedating” antihistamines (e.g. diphenhydramine, clemastine fumarate, etc.) are non-sedative for me. The “non-sedating” antihistamines (loradatine, fexodenadine, ceterizine) seem far less effective, not sure why. Has any research been done with azelastine nasal spray WRT this issue? Perhaps localized treatment rather than a systemic approach would preclude weight gain (similar to inhaled oral steroids for asthma management vs prednisone).

  7. Tim says:

    Interesting, but two things that come to mind: 1) Couldn’t it simply be that overweight individuals tend to suffer from allergies more often than those of healthy weight?
    2) The newer antihistamines (like loratidine) don’t cross the blood-brain-barrier much, hence the lack of sedative effects (as opposed to, say, diphenhydramine); wouldn’t that also preclude any appetite-associated effects?


    • kaiee says:

      It doesnt matter what weight age color gender or anything like that, if you have an allergy you have an allergy this is not like being over weight and have diabeties its allergys like listen to yourself.

      • will says:

        Overweight people do breathe heavier BTW. So being overweight can cause you to need allergy medications

    • LETITIA says:

      I suffered for years with allergies, and never took any medication, then I gained 20lb within 2 months of starting on anti histamines, and when I take them now I blow up like an inflatable raft. I want to eat non stop on them… I stop taking them and I usually drop 7 lb in 10 days. I excerise consistently…. I have done a number of on and off comparisons. THESE DRUGS MAKE YOU EAT LIKE A MAD PERSON!

  8. Susanne says:

    My personal experience is that both severe allergies and the traditional antihistamines (e.g. before loratadine came around) also made you very sluggish and unmotivated to exercise, or even move much at all. I’ll have to pay attention to the appetite effect. But if you also take ephedrine-based sinus medication, as many allergy sufferers do, the side effect of those include suppressed appetite and jitteriness.

  9. Rowan says:

    In the late 1980s I participated a the drug study for Astemizole vs Terfenadine. I gained ten pounds over a six week period. I recall reading afterwards in the information disclosure which was provided with the drug after it was released for marketing in the USA indicated that 1/10 of 1% of people would gain weight.

    The drug has since been pulled in the USA. It worked really well for my allergies so I obtained it from Canada for a couple years. Each time I took it for an extended period I would gain weight, i.e. 3-5 lbs. I would lose it after not taking it for a few months.

    Nothing in my lifestyle changed which would account for weight gain.

    Needless to say I have changed to Loratidine when needed.

  10. LKL says:

    I was started this year on singulair (a leukotrine receptor antagonist) and then a steroid inhaler recently. Both work very well. While I have noticed occasional puffiness since starting the inhaler, I haven’t noticed a change from the singulair; not being a biochemist, I have no idea whether leukotrines have similar appetite inhibiting actions to histamines.

    That said, it’s possible that some of the potential weight gain of either would be offset by the increased ability (and desire) to exercise when one has a clear airway. I personally am getting out a lot more, and being more active when I’m out, since I’ve been able to breath well.

  11. Liz says:

    I have also wondered about allergy meds being associated with weight gain. And a year and a half ago, I was determined to get off all allergy meds (I have been on them all including Seldane back in the 90’s) and that is when I started doing a sinus rinse. Every time I hear someone mention there problems with chronic allergies, I go into sales/promotion mode for using a sinus rinse (even though I don’t work for the company and in no way profit from my sales pitch). I have always had allergies and they have progressively gotten worse as I have gotten older. But the sinus rinse has truly been a miracle for me. I don’t get any of the usually allergy symptoms (constant sneezing, itchy eyes, dry throat, runny nose, etc) except for a few days in summer and fall when pollen and mold counts are extremely high. I would highly recommend this non-drug therapy to anyone with allergies. Try it for at least two weeks and I think you will be amazed. I do it every day all year long, but I know lots of other folks who just use it when their allergies are having an extreme reaction. I haven’t had to take any allergy meds since starting this regimen.

  12. Christa says:

    Wow! I haven’t noticed an increase in appetite – but I plan on paying closer attention to this. I did however notice a marked increase when I was prescribed a decongestant nasal spray to clear up stuffiness that was affecting my ear. Nothing was mentioned in the literature about it, but it was pretty clear to me. I felt as though I was getting the munchies akin to having smoked a joint (which I don’t do anymore!) :) I got rid of that medication as soon as I could. As for my seasonal allergies, well, I’ll probably still have to take antihistamines, but I will perhaps keep tabs on how they make me feel, appetite-wise. Thanks for this post! Oh, and yes, I agree with the nasal rinse – I’m a big neti pot user and promoter also!!

  13. Amy says:

    I’ve been taking antihistamines for the last couple of months straight. Warmer temperatures in my area have made me into a ball of sneezing snot. I’ve also recently had extreme appetite and blood sugar fluctations, I never would have thought the two could be connected. With the two, along came weight gain… the blood sugar drops left me too braindead to think clearly until after I had stuffed something in my mouth – usually a piece of homemade bread.

    I’m going to try to stay off of these for a couple of weeks and see that helps any. Maybe I can lose some of the accumulated weight by sneezing myself thin, ha!

  14. LKL says:

    I agree with you that a sinus rinse can work wonders, and just feels good. It’s not always enough (I’d have to do it every 15 minutes or so to feel good all day long, when things are flared up), but it definitely clears out the mold and pollen for a little while.
    Last winter I was out of training for about 4 months straight due to allergies, even using a neti pot a couple of times a day; with my current meds, I’m back in the dojo and feel good.

  15. P Anderson says:

    I realized years ago that antihistamines greatly increase my appetite. I’ve had allergies all my life. It has nothing to do with tending to gain weight because you have allergies, or being less active. I want to eat non-stop when taking antihistamines!

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  17. Martha Paul says:

    I found this site researching allergy pills and appetite. I started taking Zyrtec on a daily basis this spring and I have to fight a constant feeling of hunger. I’m going to try a different medication, or take it only when I’m really miserable.

  18. Kevin says:

    I have also noticed this effect of antihistamines, as well as the the well-known “drowsiness/lower your IQ by twenty points” effect. We’ve just got to love modern medicine! For every problem it solves, it creates two or more others. The miracle of modern medicine consists of our getting to choose in which way we want to be miserable.

    When modern medicine finally decides to come out of the Stone Age, or to exist to serve something other than the profit margins of the pharmaceutical industry, it will undertake systematic research into the likely cause of allergies: The deleterious effects of environmental toxins and food additives on our immune systems. In the meantime, however, I am certainly not going to hold my breath waiting for this to occur, so I’ll follow the paradigm and choose my preferred form of misery, I suppose!

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  22. Pat says:

    I took Claritin last night and am WAAAY hungrier right now than normal. I’ve noticed this happening before. I do not use antihistimes regularly. I was searching google to see if there was a connection and I found this blog.

    I put a lot of effort into a diet that keeps my blood sugar from tanking out, so I always pay close attention when I feel hungry so I can figure out what I did that caused it. (no, I’m not diabetic. Just have a lifelong problem with low blood sugar).

  23. Kym says:

    Two years ago, I moved to a new city and had horrible red eyes for months and I started taking Reactine and Aerius and gained almost 15 pounds within just a few months, which is very unusual for me and I then noticed that I was always hungry even after I had eaten. I correlated my antihistamine use and my hunger pangs, so when I discontinued all antihistamine, I lost all that weight within a few months and was back to normal. They definitely affect appetite in alot of people.