Can Antihistamines Like Zyrtec Cause Weight Gain?
Key takeaways:
Antihistamines are used to treat many conditions, including allergies, sleeping problems, and motion sickness. They work by blocking histamine, a natural chemical in your body.
Histamine plays a role in our appetite. When antihistamines block histamine, our appetite can increase. This, plus side effects like drowsiness, could lead to weight gain.
Your risk of gaining weight from antihistamines may depend on many factors. But a healthy diet, physical activity, and other lifestyle factors can help you manage your risk.
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Antihistamines are a common treatment for allergies as well as many other health conditions. If you’ve ever taken one, you might have experienced some of their side effects. Drowsiness is one that most people know about. But there have been concerns about weight gain, too.
Some research suggests there’s a potential link between antihistamines and weight gain. But experts don’t know for sure if this is the case.
What are antihistamines?
Antihistamines are a class of medications that are used to treat a variety of medical conditions. They block a chemical called histamine in your body, which can help treat different symptoms.
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You might be most familiar with antihistamines being used to treat allergies and itching. But they’re also commonly found in over-the-counter (OTC) sleep aids, cough and cold products, and motion sickness pills. Some are only available with a prescription.
Not all antihistamines are the same. Some are known to cause more side effects than others. First-generation antihistamines, like diphenhydramine (Benadryl), are known to cause drowsiness. Second-generation antihistamines, like cetirizine (Zyrtec), tend to be less drowsy. Below are common first- and second-generation antihistamines.
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Can antihistamines cause weight gain?
The short answer: Yes.
In fact, cyproheptadine has been used to help people gain weight by stimulating their appetite. But why does this happen, and is it the same across all antihistamines?
It’s not fully understood why antihistamines might cause weight gain. But histamine is thought to be involved due to its effect on appetite. Normally, histamine release in your body reduces your food intake. This is because it makes you feel less hungry.
Antihistamines work by blocking histamine. And animal studies have shown that blocking histamine may result in eating more than normal. What’s more, antihistamines can cause drowsiness, which can make you less active.
A 2010 observational study found that adults taking antihistamines had a higher average weight compared to people who weren’t taking them. They also had a larger waist circumference. This type of study doesn’t confirm a relationship between antihistamines and weight gain. But it suggests there may be a link. More research is needed to know for sure.
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Whether taking an antihistamine causes weight gain may depend on many factors. Lifestyle factors and your diet may play a role. And weight gain may be more likely if you’re taking antihistamines long-term.
Which antihistamines cause the most weight gain?
There haven’t been studies comparing the effects of antihistamines on weight. So, we don’t have definitive proof if one causes more weight gain than another.
But older antihistamines (e.g., diphenhydramine) cause more drowsiness than newer antihistamines. When you feel drowsy, you may be less likely to be active and burn calories.
Which antihistamines are least likely to cause weight gain?
We also don’t know for sure which antihistamines are least likely to cause weight gain. Second-generation antihistamines, like loratadine, may be less likely to keep you on the couch. But that doesn’t mean they won’t stimulate your appetite.
That said, short-term antihistamine use likely won’t be an issue. If you need to take one regularly, talk to your healthcare provider if you’re concerned about weight gain.
Can you prevent weight gain from antihistamines?
Many factors are involved in maintaining a healthy body weight. If you’re concerned about weight gain from taking an antihistamine, there are a few things you can do:
Limit your antihistamine use. Short-term courses of antihistamines may be less of an issue compared to long-term use. In some cases, it's not possible to take them short-term. But if you can, only take them when needed.
Focus on lifestyle factors. Make sure you’re eating a healthy diet, exercising regularly, and getting enough sleep.
Keep hydrated. Antihistamines can cause dry mouth, making you feel thirsty. And it’s easy to confuse thirst with hunger. Start by drinking water to help you tell the difference.
Be mindful of snacking. Antihistamines might cause you to feel more hungry. Try reaching for healthy snacks throughout the day. Foods high in fiber, like oats, whole grains, and nuts, could help you feel fuller longer.
Keep a food diary. A food diary may help you track what and how much you’re eating.
Ask about alternatives. Speak to your healthcare provider about alternative treatment options. There may be options that aren’t associated with weight gain. They may also suggest trying a different antihistamine to see if that makes a difference.
Are there alternatives to antihistamines that don’t cause weight gain?
Depending on why you’re taking an antihistamine, there may be other treatment options you could try instead. Your healthcare provider can help you navigate your options.
For example, some medications used for allergies aren’t generally associated with weight gain. These include nasal sprays like fluticasone (Flonase) and anti-allergy eye drops (e.g., cromolyn).
However, OTC antihistamines are commonly used to treat long-lasting conditions, like chronic hives. In this case, it may be better to manage potential weight gain through lifestyle changes. If not, your healthcare provider may try a different antihistamine or recommend prescription medication options.
Before changing your treatment, check with your healthcare provider first. They can help guide you to alternatives that may have a lower chance of causing weight gain.
The bottom line
The relationship between weight gain and antihistamine use isn’t fully clear. Some causes could be increased appetite and drowsiness leading to less physical activity.
A short course of antihistamines probably won’t cause issues with weight changes. But you might see weight gain with regular use. If you’re worried about weight gain, speak to your healthcare provider about alternative treatment options or ways to manage this side effect.
Be mindful about how long you’re taking an antihistamine. If you need to take one for a long period of time, a healthy lifestyle can help you manage potential weight changes.
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References
Díaz, N., et al. (2019). Central histamine, the H3-receptor and obesity therapy. CNS & Neurological Disorders - Drug Targets.
Harrison, M., et al. (2019). Use of cyproheptadine to stimulate appetite and body weight gain: A systematic review. Appetite.
Jørgensen, E., et al. (2007). Histamine and the regulation of body weight. Neuroendocrinology.
Ratliff, J., et al. (2011). Association of prescription H1 antihistamine use with obesity: Results from the National Health and Nutrition Examination Survey. Obesity.
Sakata, T., et al. (1997). Hypothalamic neuronal histamine: Implications of its homeostatic control of energy metabolism. Nutrition.
Slavin, J. (2005). Dietary fiber and body weight. Nutrition.
