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Which Drugs Cause Weight Gain?

Medically reviewed by Leigh Ann Anderson, PharmD. Last updated on Oct 7, 2023.

Some common medicines that may cause you to gain weight include some type 2 diabetes drugs like insulin or glyburide (Diabeta), certain antidepressants such as amitriptyline or paroxetine (Paxil), antipsychotic medicines like clozapine (Clozaril), some antihistamines like diphenhydramine (Benadryl) and corticosteroid drugs like prednisone.

Losing weight, or maintaining a healthy weight, can be a battle for many patients. Aging, lack of exercise, and food choices are all culprits in the battle to keep weight down. But medicines can cause weight gain too, and in some cases may require a therapy change.

15 common medicines that can cause weight gain

Learn More: Check to see if your medicine causes weight gain

Why do medicines cause weight gain?

If you are taking a prescribed medication for a medical condition, and it's causing weight gain, that almost seems unfair. Diabetes drugs, antidepressants, antihistamines and even some pain medications can all increase weight. So why does this happen?

To start, certain common medical conditions are often treated with prescription drugs that may add on unwanted pounds, and include mental health disorders like schizophrenia, depression, OCD or bipolar disorder, diabetes, high blood pressure, epilepsy and seizures, allergies, or pain and inflammation.

Some medications cause weight gain more commonly than others. For drugs that do cause weight gain, not all patients will have this side effect. However, it is important to understand your risk for added pounds and what you can do.

Reasons why your medicine might cause weight gain include side effects like:

For many drugs, it is not known exactly what causes weight gain. It is often difficult to distinguish between weight gain from a drug and weight gain from other reasons, like diet or lack of exercise, because weight gain is usually a slow process. Plus, some conditions, like depression, can lead to weight loss or weight gain, depending upon the individual.

However, if a rapid weight gain or rapid fluid retention occurs in a short period of time, a physician should be contacted for evaluation, especially if you are at risk for heart or lung disease, chronic heart failure or high blood pressure.

What problems occur from drug-related weight gain?

Being overweight can result in several common health problems:

Is my medication causing me to gain weight?

If you have started a new medication in the last 6 months to a year, and put on more than a few pounds, think about ways this might have happened:

Patients should also ask their healthcare provider about the potential for weight gain before a new medication is prescribed. And remember, medications may affect patients differently, and not every patient will gain weight. Worries about weight gain or loss should not usually be the main deciding factor for a needed medical treatment.

How is medication-related weight gain treated?

If you do gain a few pounds, don't let it affect your self-esteem. The weight may come off if you are able to discontinue or change to a drug that does not boost your weight, add daily exercise, or change your eating habits, but only do so under your doctor's advice.

Learn more: Obesity and Weight Loss Resource Center

Drugs and drug classes

Here are some drug classes, and common drugs in each class, that may lead to weight gain. When possible, an alternative medicine is listed, but many medications cannot be changed or stopped, so follow your health care providers advice. These are not complete lists of drugs that might lead to weight gain, so if you have concerns, talk to your doctor.

1. Antidepressants

Usually, a physician can choose among many alternatives in the antidepressant class if weight gain is an issue. Some antidepressants may lead to weight gain by interfering with the neurotransmitter serotonin that may control appetite. Others can elevate antihistamine effects and appetite, or may cause sedation and fatigue that lowers your level of activity.

Weight gain

Older antidepressants, known as tricyclic antidepressants (TCAs) are notorious for increasing appetite and for causing weight gain.

TCAs affect neurotransmitters in the brain and also exhibit antihistamine activity, which can boost appetite. TCAs are also used to treat migraine headaches, anxiety, insomnia, and other conditions.

Examples of TCAs that can commonly lead to weight gain are:

Clomipramine (Anafranil) can also lead to weight gain, but it is approved for treatment of obsessive-compulsive disorder (OCD).

Another commonly used class of antidepressants, the selective serotonin reuptake inhibitors (SSRIs), are not always associated with weight gain. However, some frequently prescribed SSRIs, like paroxetine (Paxil) or fluvoxamine (Luvox) can cause this side effect.

Mirtazapine (Remeron) is an atypical antidepressant that boosts serotonin, like SSRIs, but also has an antihistamine effect that may boost appetite and lead to significant weight gain.

In mirtazapine clinical studies, weight gain was reported in 12% of adults (with a weight gain of more than 7% reported in 8% of adults) and in half of pediatric patients. Increased serum cholesterol (15%) was also documented.

Monoamine oxidase inhibitors (MAOIs), an older class of antidepressant not frequently prescribed anymore, are not linked with significant weight gain.

Weight loss, neutral or slight weight gain

Bupropion (Wellbutrin SR) is antidepressant that is actually associated with weight loss; it's also linked with less sexual side effects than some other antidepressants like the SSRIs.

Venlafaxine (Effexor XR) and duloxetine (Cymbalta) are classified as selective serotonin and norepinephrine reuptake inhibitors (SNRIs) and have more neutral effects on weight gain. Other SNRIs also have a lesser effect on weight gain compared to TCAs or even SSRIs.

Vortioxetine (Trintellix) is an SSRI / serotonin modulator approved in 2013. In studies, it had no significant effect on body weight as measured by the mean change from baseline in either short-term or longer-term (6 month) research trials accessing weight gain. However, some reports have been received of weight gain since approval, so discuss this side effect further with your doctor.

Other serotonin modulators such as nefazodone, trazodone (Desyrel), or vilazodone (Viibryd) also have low to no effect on weight gain.

Some SSRIs are also more weight neutral or may lead to moderate weight loss in the first 6 months.

2. Antihistamines

Antihistamines are commonly used to treat conditions such as allergic rhinitis (hay fever), cold or flu symptoms, food allergies, hives (urticaria), drug allergies, and insect bites or stings. Newer antihistamines usually cause less drowsiness than the 1st generation medicines, and are usually preferred to help prevent seasonal hay fever, animal dander allergies, and eye allergies to pollen.

Newer 2nd generation antihistamines, such as cetirizine (Zyrtec), loratadine (Claritin, Alavert) and fexofenadine (Allegra) selectively antagonize histamine H1 receptors.

Cyproheptadine, an older H1 antihistamine, has actually been used to increase weight gain in patients with chronic diseases and failure to thrive. The 1st generation diphenhydramine (Benadryl) is also linked with weight gain when used on a long-term basis. Other 1st generation antihistamines include brompheniramine, chlorpheniramine, and hydroxyzine.

Alternatives

Nasal corticosteroids such as triamcinolone nasal spray (Nasacort Allergy 24HR Nasal Spray) or fluticasone nasal spray (Flonase Allergy Relief) won't cause weight gain and may be better options for hay fever or other allergy symptoms, especially if weight gain is a concern.

Although nasal corticosteroid sprays are often preferred for allergies (allergic rhinitis), the antihistamine nasal sprays such as azelastine (Astepro, Astelin) and olopatadine (Patanase) are also available.

3. Antipsychotics and Mood Disorder Treatments

These drugs are used to treat mental health conditions such as schizophrenia, bipolar disorder, or as an add-on treatment with an antidepressant for difficult-to-treat depression. Although all of the drugs in the antipsychotic class have been shown to produce some metabolic and weight changes, each drug has its own specific risk profile.

Many antipsychotics are well-known to cause weight gain. Research by Huang and colleagues has shown an enzyme called AMP-kinase is elevated in the brain of patients who use antipsychotics. AMP-kinase can block the brain histamine-1 receptor, which can increase appetite and weight gain.

However, for mental health disorders, drug treatment may be absolutely necessary. The risk of stopping the drug may be greater than the risk associated with weight gain. If you are taking any prescription, do not stop treatment without first speaking to your doctor.

Patients taking antipsychotic drugs should have their weight, waist circumference, lipids, blood pressure, and blood glucose (sugar) monitored at the recommended intervals.

Weight gain

Antipsychotics are frequently linked with weight gain.

Examples in this drug class include the atypical antipsychotics such as olanzapine (Zyprexa), risperidone (Risperdal), aripiprazole (Abilify) and quetiapine (Seroquel). Brexpiprazole (Rexulti), approved in 2015, is also linked with weight gain: In the long-term studies, 30% of patients demonstrated a ≥7% increase in body weight, and 4% demonstrated a ≥7% decrease in body weight.

Clozapine (Clozaril), an older, atypical antipsychotic has also been associated with significant weight gain. Patients may gain from 7% to 10% of their body weight. These drugs can have antihistaminic activity and also block serotonin, which may contribute to the weight gain effect.

The original "typical" antipsychotics such as haloperidol (Haldol), chlorpromazine, fluphenazine, and thioridazine can cause weight gain, but these drugs are used less frequently due to abnormal movement disorders that can occur. Haloperidol and fluphenazine have the lowest risk of the 1st generation agents.

Many of the antipsychotics may impair glucose (sugar) control and lead to insulin resistance, impaired glucose tolerance and type 2 diabetes. However, these drugs may be necessary for treatment of bipolar disorder, severe depression, or schizophrenia and for the safety of the patient. Patients or caregivers must speak with the physician before stopping treatment.

Weight neutral or less risk of weight gain

4. Beta blockers

Weight gain, especially if it's rapid, can be a medical concern with any heart drug. If your weight gain is due to fluid retention (edema), it may be dangerous for your heart and you should contact your doctor right away. You may need a special medicine called a diuretic to help with your fluid (water) retention.

Beta blockers are an older class of heart drug used to treat high blood pressure, chest pain (angina), and protect or prevent the heart from a heart attack.

Other blood pressure medications like the angiotensin-converting enzyme inhibitors (ACE inhibitors), angiotensin II receptor blockers (ARBs), or calcium channel blockers are less likely to cause weight gain, and may be an option for you.

5. Birth Control

In general, the birth control pill is not linked with weight gain, especially the newer pills with lower doses of estrogen and progestin. However, higher doses of estrogen or progestin-only birth control can cause weight gain.

The birth control shot known as medroxyprogesterone (Depo-Provera) that is given every 3 months can cause significant weight gain in some women.

6. Corticosteroids

Corticosteroid ("steroid") medications are used for many different conditions (asthma, allergies, arthritis, acute injury) to help lower inflammation, pain and swelling. Often they are used short-term or the dose is slowly tapered down, which can help lessen side effects. Long-term use of corticosteroid drugs can be linked with many more serious side effects, and is avoided when possible.

Steroids can affect the metabolic rate and lead to increased appetite and overeating. This class of drug can lead to extra deposits of fat in your midsection (stomach area).

Oral corticosteroids (glucocorticoids) may carry a risk of weight gain with high dose and long-term use. Oral corticosteroids might be used for severe asthma or painful inflammatory conditions such as rheumatoid arthritis or inflammatory bowel disease.

Examples of corticosteroids include prednisone, methylprednisolone (Medrol Dosepak), prednisolone (Orapred) and triamcinolone (Kenalog).

Weight neutral

Local injectable corticosteroids, such as injections in the knee joint or spinal column for inflammation, and inhaled corticosteroids used for asthma, are not associated with weight gain.

For pain that requires longer-term treatment, such as mild to moderate arthritis pain, acetaminophen (Tylenol) or an NSAID like ibuprofen (Advil, Motrin) or naproxen (Aleve) may be alternatives.

7. Diabetes medications

Diabetes drugs are used to help control blood sugar by helping to release more insulin from the pancreas or making the insulin more responsive when it is released. Insulin itself can also be injected.

Weight gain

Some drugs used in the treatment of type 2 diabetes can lead to weight gain and fluid retention.

Certain oral medications for type 2 diabetes, such as glyburide (DiaBeta), glimepiride (Amaryl) and glipizide (Glucotrol), members of the sulfonylurea class, can lead to weight gain. These agents lower blood glucose by stimulating insulin release, which can result in an elevated appetite.

Type 2 diabetes drugs in the class known as thiazolidinediones can lead to weight gain and an increase in fat. Example drugs include pioglitazone (Actos) and rosiglitazone (Avandia). These drugs have a Boxed Warning about excessive, rapid weight gain; dyspnea (shortness of breath); and edema that may indicate the onset of heart failure.

Weight neutral

There are some type 2 diabetes treatments that are more likely to be weight neutral or associated with weight loss.

Weight loss

The glucagon-like peptide-1 receptor agonists (GLP-1 agonists), also called the incretin mimetics, are glucose-lowering drugs that have been shown to have a positive effect on weight and fat distribution.

The selective sodium-glucose co-transporter 2 inhibitors (SGLT-2 inhibitors), also glucose-lowering agents, can lead to moderate effects on weight loss, examples include:

8. Anticonvulsants, mood stabilizers and migraine medicines

Some anticonvulsant drugs can be associated with significant weight gain; up to 30 to 40 lbs (15 to 20 kg) in some cases over the long-term. Obesity itself is also linked with migraine. As obesity increases, so does the risk and severity of migraine headaches.

Weight gain

Weight loss or weight neutral

Common drugs used for migraine prevention (propranol) or seizures (Depakote) can cause weight gain. Since these medicines are typically used long-term, the risk is greater. There are alternatives you might to discuss with your doctor.

Table: Common Medicines That Cause Weight Gain

Drug Class or Use Medication Generic Name
SSRI Antidepressant Paxil paroxetine
SSRI Antidepressant Zoloft sertraline
Tricyclic Antidepressant Elavil (brand discontinued) amitriptyline
Antidepressant Remeron mirtazapine
Antipsychotic Clozaril clozapine
Antipsychotic Zyprexa olanzapine
Antipsychotic Risperdal risperidone
Antipsychotic Seroquel quetiapine
Mood stabilizer Lithobid lithium
Seizure Disorder / Migraines / Mood Stabilizer Depakene, Depakote valproic acid, divalproex
Seizure Disorder Neurontin gabapentin
Seizure Disorder Tegretol carbamazepine
Beta Blocker (blood pressure) Lopressor metoprolol
Beta Blocker (blood pressure) Tenormin atenolol
Beta Blocker (blood pressure) Inderal propranolol
Beta Blocker (blood pressure) Norvasc amlodipine
Alpha-2 adrenergic agonists (blood pressure) Catapres clonidine
Thiazolidinediones (diabetes) Actos pioglitazone
Thiazolidinediones (diabetes) Avandia rosiglitazone
Sulfonylureas (diabetes) Amaryl glimepiride
Sulfonylureas (diabetes) Diabeta glyburide
Sulfonylureas (diabetes) Glucotrol glipizide
Insulins (diabetes) Novolog, Lantus, Humalog (various brands) insulin
Corticosteroid Medrol, Solu-Cortef prednisone, methylprednisolone, hydrocortisone
Antihistamines Allegra fexofenadine
Antihistamines Zyrtec cetirizine
Contraceptives Depo-Provera Contraceptive medroxyprogesterone

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Sources

  1. Heymsfield S, Aronne L, Eneli I, et al. Clinical perspectives on obesity treatment: Challenges, gaps, and promising opportunities. NAM Perspectives. 2018. Discussion Paper, National Academy of Medicine, Washington, DC. doi: 10.31478/201809b
  2. Health Risks of Being Overweight. National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). Accessed June 28, 2022 at https://www.niddk.nih.gov/health-information/weight-management/adult-overweight-obesity/health-risks
  3. Wilding, J.P.H. Medication use for the treatment of diabetes in obese individuals. Diabetologia. 2018:61;265–272. Accessed June 28, 2022 at https://doi.org/10.1007/s00125-017-4288-1
  4. Fields T. Hospital for Special Surgery. Steroid Side Effects: How to Reduce Corticosteroid Side Effects. 4/11/2017. Accessed June 28, 2022 at https://www.hss.edu/conditions_steroid-side-effects-how-to-reduce-corticosteroid-side-effects.asp
  5. Kyle T, Kuehl B. Prescription medications and weight gain: what you need to know. ObesityAction.org. Accessed June 28, 2022.
  6. Antihistamines and weight gain. Ask the Expert. American Academy of Allergy, Asthma & Immunology. Accessed June 28, 2022 at https://www.aaaai.org/ask-the-expert/antihistamines-weight-gain
  7. Blumenthal S, Castro V, Clements C, et al. An Electronic Health Records Study of Long-Term Weight Gain Following Antidepressant Use. JAMA Psychiatry. 2014;71(8):889–896. 
  8. Ratliff JC, Barber JA, Palmese LB, et al. Association of Prescription H1 Antihistamine Use With Obesity: Results From the National Health and Nutrition Examination Survey. Obesity 2010;18:2398-2400.
  9. Kim S, Huang A, Snowman A, et al. Antipsychotic drug-induced weight gain mediated by histamine H1 receptor-linked activation of hypothalamic AMP-kinase. Proceedings of the National Academies of Sciences. 2007;104:3456-59.
  10. Cheskin L, et al. Prescription medications: a modifiable contributor to obesity. South Med J. 1999;92:898-904.
  11. The US Centers for Disease Control and Prevention (CDC). Overweight & Obesity. Updated November 10, 2021. Accessed June 23, 2022 at https://www.cdc.gov/obesity/data/index.html
  12. Pereira, M.J., Eriksson, J.W. Emerging Role of SGLT-2 Inhibitors for the Treatment of Obesity. Drugs 2019:79;219–230. Accessed June 23, 2022 at https://doi.org/10.1007/s40265-019-1057-0
  13. Cantú TG, Korek JS. Monoamine oxidase inhibitors and weight gain. Drug Intell Clin Pharm. 1988;22(10):755–759. doi:10.1177/106002808802201002
  14. Fava M. Weight gain and antidepressants. J Clin Psychiatry. 2000;61 Suppl 11:37–41.

Further information

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