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Which Drugs Cause Weight Gain?

Medically reviewed by Leigh Ann Anderson, PharmD. Last updated on Feb 8, 2020.

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. However, some very common medications can also lead to 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 what are your options?

Weight problems are already common in the general public. The US Centers for Disease Control and Prevention (CDC) notes that overall, 39.8% percent of U.S. adults (or 93.3 million) are obese. When looking at children aged 2 to 19 years of age, about 18.5% (or 13.7 million) are obese.

For example, these common medical conditions are often treated with prescription drugs that may add on unwanted pounds:

Some medications are more common than others to lead to weight gain. And 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.

Learn More: Do My Medications Cause Weight Gain?

Why do medicines cause weight gain?

Common reasons why your medicine might cause weight gain include:

  • increased appetite: drugs that trigger increases in appetite may work in the brain and affect the satiety (fullness) center. 
  • fluid (water) retention
  • elevated fat storage - for example, insulin can increase fat storage
  • slowed metabolism
  • fatigue or weakness, which may lead to less activity, exercise, and calories burned.

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 it can be a slow process. Some conditions, like depression, can lead to weight loss or weight gain, depending upon the individual.

If a rapid weight gain 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.

Related: Prediabetes: Am I At Risk? 

What problems occur from drug-related weight gain?

Being overweight may lead to, or worsen, several common health problems:

  • type 1 diabetes
  • type 2 diabetes
  • prediabetes
  • osteoarthritis
  • high blood pressure (hypertension)
  • high cholesterol
  • metabolic syndrome
  • heart disease or stroke
  • cancer
  • sleep apnea or other respiratory diseases
  • fatty liver disease
  • kidney disease
  • pregnancy problems.

Learn more: Obesity and Weight Loss Resource Center

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:

  • Have you been eating more calories, either in the types of food you eat or the amount of food you eat? What about your salt intake?
  • Did you change the amount of daily activity you do, such as less exercising or more sitting at a desk or computer?
  • Have you had a significant change or stressor in your life that may have lead to overeating?

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 needed medical treatment.

How is medication-related weight gain treated?

  • Do not stop taking any medication without talking to your doctor first. If you have a concern about weight gain with a medicine, make an appointment to discuss your concerns.
  • In many cases, you may be able to switch to a different medication or use a lower dose of the drug. Together, you and your doctor can make sure the benefits of the medicine outweigh the risks from any weight gain.
  • You may need to have a multi-faceted approach too: an increase in daily exercise, attention to diet, and limiting salt intake may be recommended. Limiting portion sizes, drinking plenty of water throughout the day, and eating slowly are other tips.

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 exercise, or change your eating habits, but only do so under your doctor's advice.

Drugs that may cause weight gain

Here are some drug groups, 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.


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 increase antihistamine effects and appetite, or may cause sedation and fatigue that lower levels 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 amitriptyline (Elavil), trimipramine (Surmontil), and imipramine (Tofranil), doxepin.
  • 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, Luvox CR) 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 also lead to significant weight gain.
    • In 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) are not linked with significant weight gain.
    • Of the antidepressant MAOI class, phenelzine (Nardil) may be the most likely to lead to an increase in weight (1% to 10% of patients).
    • Rasagiline (Azilect) and selegiline (Eldepryl, Zelapar) are anti-parkinson disease MAOI agents that not used for depression. They may commonly lead to weight loss in 1% to 10% of patients.

Weight loss, neutral or slight weight gain

  • Bupropion (Wellbutrin) is antidepressant that is actually associated with weight loss; it's also linked with less sexual side effects than others like the SSRIs.
  • Venlafaxine (Effexor) 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, or vilazodone 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.
    • SSRIs that may lead to lower weight gain include: fluoxetine (Prozac), citalopram (Celexa), escitalopram (Lexapro), or sertraline (Zoloft).
    • For some people, the weight loss at the outset may be temporary, and weight gain may occur later in therapy.  


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 type, 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. These drugs, which are available without a prescription, have been associated with weight gain. Antihistaminic activity can also boost appetite, as noted with several other drugs that cause weight gain.
    • A study compared the use of antihistamines and the risk of obesity. Users of cetirizine (Zyrtec) and fexofenadine (Allegra) had significantly greater weight, BMI, waist circumference, and insulin levels.
    • Cetirizine (Zyrtec) can lead to drowsiness in roughly 10% of patients, more than other 2nd generation antihistamines.
  • 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.


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

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 more severe depression. Although all of the drugs in the antipsychotic class have been shown to produce some metabolic 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 will boost appetite and may lead to weight gain. However, for many mental health disorders, drug treatment may be absolutely necessary and the risk of stopping the drug may be greater than the risk associated with weight gain.

Patients taking antipsychotic drugs should have their weight, waist circumference, lipids, blood pressure, and blood glucose (sugar) monitored at 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), a newer atypical antipsychotic, 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 (Thorazine), fluphenazine, and thioridazine (Mellaril) can cause weight gain, but these drugs are used less frequently due to movement disorder side effects. 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

  • While no antipsychotic is completely void of metabolic side effects, ziprasidone (Geodon), lurasidone (Latuda), and pimavanserin (Nuplazid) are more weight neutral antipsychotics. Nuplazid is indicated specifically for psychosis that is related to Parkinson's disease.

Antihypertensives (beta blockers)

Weight gain, especially if it's rapid, can be a 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.

  • Beta blockers has long been known to lead to weight gain. Common examples of this class are propranolol, metoprolol (Lopressor) and atenolol (Tenormin).
    • Many of the older beta blocker drugs can lead to fatigue, which may be responsible for some of the weight gain. Patients may be tired, have lack of energy, and in general slow down, which may affect the number of calories burned each day.
  • 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 option for you.

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.


Corticosteroid 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 on a tapering dose, which can help lessen side effects. Long-term use of corticosteroid drugs can be linked with many more serious side effects.

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).

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.

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.
  • Injectable insulin (itself can also lead to significant weight gain, as insulin use allows glucose to enter your cells instead of staying in your blood. Too many calories in the form of glucose will lead to weight gain. Excess glucose ends up as fat if it's not burned off with exercise.
  • Drugs in 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/or edema that indicate the onset of heart failure.

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

Weight neutral

  • Metformin (Fortamet, Glumetza, Riomet), typically the first drug used in the treatment of type 2 diabetes. Metformin tends to be weight neutral, meaning there's no gain or loss of weight due to the drug.
  • Dipeptidyl Peptidase 4 (DPP-4) Inhibitors: alogliptin (Nesina), linagliptin (Tradjenta), sitagliptin (Januvia), and saxagliptin (Onglyza) also have a more neutral effect on weight.
  • The alpha-glucosidase inhibitors, such as acarbose (Precose) and miglitol (Glyset) also tend to be more weight neutral. 

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.
    • Examples include: albiglutide (Tanzeum), dulaglutide (Trulicity), exenatide (Bydureon, Byetta), liraglutide (Victoza), lixisenatide (Adlyxin), and semaglutide (Ozempic, Rybelsus).
    • In fact, one brand of liraglutide, known as Saxenda, is a GLP-1 agonist used specifically for weight loss, but it's not approved for use in diabetes. Only one GLP-1 agonist should be at a time.
  • The selective sodium-glucose co-transporter 2 inhibitors (SGLT-2 inhibitors), also glucose-lowering, can lead to moderate effects on weight loss: examples include canagliflozin (Invokana), empagliflozin (Jardiance), ertugliflozin (Steglatro) and dapagliflozin (Farxiga).

Anticonvulsants and Mood Stabilizers

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.

Weight gain

  • Divalproex (Depakote, Depakene) is used to treat epilepsy (seizures), bipolar disorder and for migraine prevention. Other agents that can affect weight include carbamazepine (Carbatrol, Tegretol, Epitol), pregabalin (Lyrica) and gabapentin (Neurontin, Horizant).
  • Lithium (Lithobid) is also commonly used for mood disorders and is associated with a significant weight gain. Up to 65% of patients may gain over 20 lbs (10 kg) after many years of use.

Weight loss or weight neutral

  • Topiramate (Qudexy XR Sprinkle, Topamax), used for seizures and migraine headaches, might actually cause weight loss in some people. Other options might include zonisamide (Zonegran) or  lamotrigine (Lamictal).

Table 1. Medications That May Cause Weight Gain

Drug Class or Use Medication Generic Name
SSRI Antidepressant Paxil paroxetine
SSRI Antidepressant  Zoloft sertraline
Tricyclic Antidepressant Elavil 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 Deltasone, Medrol, Solu-Cortef prednisone, methylprednisolone, hydrocortisone
Antihistamines Allegra fexofenadine
Antihistamines Zyrtec cetirizine
Contraceptives Depo-Provera Contraceptive medroxyprogesterone

Learn More:

See Also


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  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.
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Further information

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