Could Your Medication Make You Eat Too Much?

By Temma Ehrenfeld @temmaehrenfeld
January 23, 2024
Woman taking a pill

Some common medications, such as antihistamines and antidepressants, encourage your appetite and weight gain. Here's what you should know and can do.

Many people, especially if they’re allergic to a pet or dust, take antihistamines every day. They might not realize that using their medication may be contributing to weight gain.

Drugs can affect weight in many ways.


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Increased appetite

Histamine is a body chemical that turns off hunger signals, which might explain why antihistamines are linked to obesity.

The antihistamine effect of the antipsychotic olanzapine (Zyprexa) could be why it causes patients to gain weight.

If you’re just dealing with allergies, loratadine (Claritin) may have less of an effect on your appetite, since it does not cross into your brain. You can also try a nasal steroid spray like fluticasone propionate (Flonase) instead.

Corticosteroids like prednisone also stimulate appetite. Pharmacists recommend taking them along with food, ideally with protein. Almonds or yogurt are good options and may keep you from overeating. Most of the time, you won’t be taking steroids for longer than two weeks.

Weight gain is a problem with antidepressants, too. The tricyclic antidepressant amitriptyline (Elavil) is often prescribed for migraines and irritable bowel syndrome. Nortriptyline (Pamelor) is sometimes used to treat panic or anxiety disorders, some kinds of pain, and to help people quit smoking.

If you are treating depression, bupropion (Wellbutrin) or duloxetine (Cymbalta) are linked to weight loss. Fluoxetine (Prozac) is less likely to affect your weight either way.

Fluid retention

Are your legs or feet swollen or puffy? Drugs can make your body retain more salt and water, which happens to about one in 10 people who take amlodipine (Norvasc) to lower their blood pressure.

Fluid retention is a side effect of:

  • The diabetes drugs pioglitazone (Actos) and rosiglitazone (Avandia)
  • The steroid prednisone
  • The estrogen in oral contraceptives
  • The NSAID pain relievers like ibuprofen (Motrin, Advil)
  • Drugs for nerve pain

Talk to your doctor about other options, or try to limit the dose or time you’re on the medication.

Increased fat storage

Insulin stimulates your body to create fat cells, where you store fat.

Slowed metabolism

Beta blockers for high blood pressure slow down the rate at which your body burns calories.

Trouble exercising

If a drug makes you sleepy, you’ll have a harder time exercising. That’s a side effect of some antihistamines.

Eating more sweets

This is a common side effect of opioids, which can also lead to addiction.

What you can do

If you start taking a new medication and gain weight within the first six months, talk to your doctor.

Your doctor is likely to ask you about your exercise, diet, and sleep habits. Have any of those routines changed? Keeping a food and exercise diary can help you zero in on changes you may not have noticed.

If you have concerns, see this list of drugs that encourage weight gain.


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January 23, 2024

Reviewed By:  

Janet O’Dell, RN