10 Common Medications That May Cause Weight Gain

1. Tricyclic Antidepressants

These medications include amitriptyline (Elavil), doxepin (Silenor), and nortriptyline (Pamelor). “As a class, these drugs may increase appetite to stimulate weight gain,” says Jessica Nouhavandi, PharmD, the co-CEO and cofounder of Honeybee Health, in Culver City, California. If you’re on antidepressants, don’t stop taking them abruptly; discuss it first with your doctor and develop a plan that will best support your mental health, notes Harvard Health Publishing. If weight gain is making you want to stop taking your medication, you can talk to your doctor about switching to another class of antidepressants. “Bupropion (Wellbutrin) or duloxetine (Cymbalta) are more associated with weight loss, while fluoxetine (Prozac) is considered weight neutral,” says Dr. Nouhavandi.

2. Corticosteroids

Oral corticosteroids, such as prednisone (Deltasone), treat a range of conditions, from asthma and arthritis to back pain and lupus, says Dr. Ellis. “These have a lot of side effects, one of which is an increased appetite, fluid retention, and an altered metabolism,” she says. Pharmacists recommend taking corticosteroids along with food, and Ellis suggests a healthy, balanced snack, such as almonds or yogurt. Oral steroids are usually recommended for a short amount of time (for instance, a week or two-week dose), which limits side effects. If you have to take them long term, it may be more difficult to control your weight gain and you’ll want to be more diligent with diet and exercise, she says.

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3. Antihistamines

If you have allergies or have ever had an itchy rash, you’ve likely taken antihistamines. “Studies have shown that people who take certain antihistamines on a regular basis have a higher body weight and waist circumference compared with those who do not,” says Ellis. Research in the journal Obesity found this association with the H1 receptor antihistamines cetirizine (Zyrtec), fexofenadine (Allegra), and desloratadine (Clarinex). Why? “Histamine in the body turns off hunger signals,” explains Ellis. In contrast, antihistamines may somehow interfere with fullness signals, she says. One alternative are nasal steroid sprays like fluticasone propionate (Flonase). These work differently from oral steroids, and are generally not associated with weight gain, she says.

4. Epilepsy Medications

Drugs that treat seizures, including gabapentin (Gralise), pregabalin (Lyrica), and vigabatrin (Sabril) may increase your appetite, says Nouhavandi, potentially leading to weight gain. “If you are a patient taking one of these medications, it’s important to be aware that weight gain may be a consequence. If you feel that the medication is not for you, talk to your doctor about switching to epileptic medications that are associated with weight loss or are weight neutral,” she says. Ask about felbamate (Felbatol), topiramate (Topamax), or lamotrigine (Lamictal).

5. Beta-Blockers

Beta-blockers are commonly used to treat hypertension, says Aaron Emmel, PharmD, the founder of Pharmacy Tech Scholar in St. Augustine, Florida. Some are more likely to cause weight gain, including atenolol (Tenormin) and metoprolol (Lopressor), notes the Mayo Clinic. The reason behind an uptick on the scale isn’t clear, Dr. Emmel says, but beta-blockers can make you tired, especially as you first start taking the medication. “It slows down your heart rate and can decrease your exercise tolerance,” he says. The fatigue and discomfort during activity may make you more likely to stay sedentary, prompting weight gain. One study showed the drug may decrease metabolism, too. For that reason, the researchers suggested that individuals who are overweight or have obesity should not be prescribed beta-blockers as a first-line treatment. Instead, angiotensin-converting enzyme (ACE) inhibitors may be a better option, but talk to your doctor.

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6. SSRIs

SSRIs are selective serotonin reuptake inhibitors, a type of antidepressant, which increase levels of the neurotransmitter serotonin in the brain. Examples include escitalopram (Lexapro), paroxetine (Paxil), and sertraline (Zoloft). These may cause weight gain by affecting your appetite; also, by alleviating symptoms of mood disorders, they may also affect eating or exercise habits, says Emmel. “If you experience weight gain, talk to your physician. Weight gain usually happens early, which signals that it can become a long-term problem for you,” he says.

7. MAOI

MAOI stands for monoamine oxidase inhibitor, which treats depression by blocking a brain enzyme that breaks down mood-balancing neurotransmitters such as serotonin and dopamine. It may also be used to reduce migraine symptoms. And they may also stimulate appetite, says Nouhavandi, who notes that phenelzine (Nardil) causes the most weight gain in this class of drugs. If this is a concern for you, ask your doctor if there are alternative options.

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8. Insulin

If you’re taking insulin to treat diabetes, know that it may promote weight gain. Namely, because the hormone helps your body absorb the glucose from your bloodstream. “Glucose is a good thing — the cells in your body use it to work efficiently,” says Mitchell Howard, PharmD, a clinical assistant professor in the department of pharmacy practice at the University of Toledo in Ohio. That said, after sugar is absorbed from the bloodstream and pushed into cells, it will be converted into fat if it’s not used by your body for energy. If you’re overeating, particularly high-sugar foods (candy, desserts), you’ll gain weight, he says. If you have type 1 diabetes, you will need to take insulin. Yet if you have type 2 diabetes, lifestyle changes will help improve insulin function, and you may be able to use diet and exercise to lower (or eventually eliminate) your insulin dosage, says Dr. Howard.

9. Sulfonylureas

Another common class of diabetes medication, sulfonylureas reduce blood sugar levels by 20 percent but also cause weight gain of about 4 to 5 pounds (lb) on average, noted one study. Sulfonylureas include gliclazide (Diamicron) and glibenclamide (Glynase). These drugs stimulate pancreatic beta cells to release insulin. “More insulin in your bloodstream pushes sugar into your cells,” says Howard. In the end, they cause weight gain similar to injectable insulin. There are diabetes medications, including metformin (Fortamet) or SGLT2 inhibitors, that also promote weight loss or are weight neutral, says Howard. The type of drug that’s best for you depends on your medical history, current health status, and cost considerations, he says.

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10. Antipsychotics

These medications can be used to treat schizophrenia and bipolar disorder. One in particular, olanzapine (Zyprexa), is associated with the highest potential to gain weight compared with other antipsychotics, says Howard. What’s more, these types of drugs impair glucose function and increase cholesterol and triglycerides, putting patients more at risk for developing metabolic syndrome, according to research. Howard says lurasidone (Latuda) and ziprasidone (Geodon), two other antipsychotics, have a lower chance of causing weight gain.