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Can Prescription Drugs Lead to Weight Gain?

Medically reviewed by Leigh Ann Anderson, PharmD. Last updated on Oct 2, 2020.

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Can Some Medications Can Cause Me to Gain Weight?

Unfortunately, the answer to this question is yes. Weight gain due to medications can be just a few pounds, or it can be a more serious weight gain.

For example, some drugs that decrease inflammation like prednisone or methylprednisolone might lead to a 50 pound weight gain or more, often in the storage of fat.

In addition, weight gain from medications can worsen, or even cause, medical conditions such as:

How Do Medications Cause Weight Gain?

Weight gain can be a slow process, whether it be from drugs, food, or lack of exercise.

Exactly what causes the weight gain due to a medication is not always known.

  • Some medications can increase hunger or lead to fluid and water retention, often called edema.
  • Drugs that trigger an increase in appetite may work in the brain and change the satiety center, that alerts you when you feel full.
  • Some medications may slow you down and lead to a less active lifestyle, resulting in added pounds.

It is often difficult to tell the difference between weight gain from a drug and weight gain from other reasons. If your weight gain is sudden or concerning to you, speak with your doctor.

What Are The Risks Associated With Medication-Related Weight Gain?

The risks due to weight gain can be serious, whether it's medication-related or due to other factors.

Most importantly, weight gain may increase the chance for:

If a rapid weight gain occurs in a short period of time, a physician should be contacted for evaluation, especially if a patient has a risk for heart disease like heart failure or high blood pressure.

Some drugs may need to be stopped slowly, as stopping them quickly may lead to serious side effects. You should not stop taking any medication without first talking to your doctor.

What Can Be Done About Weight Gain With Medications?

  • If you are concerned about weight gain due to any medications, that's a good reason to contact their health care provider. It may be possible to change to a different drug that can lower this effect.
  • Even similar medications in the same drug class can lead to very different side effects.
  • Weight gain may be due to something else, too, so it's important to have your doctor examine you.

Medications can affect each patient differently, too - not every patient will gain weight, even if it is listed as a side effect of the drug. However, in some cases, patients will need to increase their level of exercise, watch their salt intake and otherwise adjust their diet.

Learn more about unexplained weight gain here.

Can Antidepressant Drugs Lead To Weight Gain?

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

  • The selective serotonin reuptake inhibitor (SSRI) class is usually weight neutral, but some drugs in this class can cause weight gain. Research suggests that fluoxetine (Prozac) may be the SSRI least likely to causes weight gain while paroxetine (Paxil) may the most problematic.
  • A physician can choose among many alternatives in the antidepressant class to minimize weight gain.
  • Mirtazapine (Remeron), an atypical antidepressant may cause significant weight gain.

Antidepressants are not always the direct cause of weight gain -- lack of exercise, altered sleep habits, unhealthy food choices, and changes in eating habits due to depression may result in added weight, too.

Which Antidepressants Are Known To Cause Weight Gain?

Tricyclic antidepressants have been associated with weight gain - common culprits include:

Most of the these SSRIs are weight neutral but can be linked with some weight gain:

Fluoxetine was associated with a weight loss of 1.3 kg (2.9 lbs) and sertraline has shown an average weight gain of 1.5 kg (3.3 lb), compared to 1.8 kg (4.0 lb) for placebo.

However, certain SSRIs like paroxetine (Paxil) may be more likely to lead to weight gain than other SSRIs. Research shows weight gain can be up to 3.6% percent of body weight before treatment (for example: about 5.5 lbs in a 150 lb person). Weight gain due to maintenance treatment with SSRIs may also lead to diabetes.

The atypical agent mirtazapine (Remeron) is linked with weight gain, roughly 1.5 kg (3.3 lbs), on average. It can also commonly lead to drowsiness compare to the SSRIs.

Bupropion (brand names include Aplenzin, Forfivo XL, Wellbutrin SR, Wellbutrin XL) is an atypical antidepressant agent that is linked with weight loss as a side effect. One study found a average weight loss of 1.3 kg (2.9 lbs). Bupropion is also used in the treatment of seasonal affective disorder and smoking cessation.

Do Antihistamines Lead To Weight Gain?

You may not know that antihistamines can also lead to weight gain. Whether this is due to direct action from the medicine, elevated appetite or a by-product of reduced activity due to sedation is not clear.

Antihistamines block histamine receptors and are commonly used for seasonal and year-round allergies. These drugs can be bought without a prescription over-the-counter. Examples include:

  • cetirizine (Zyrtec)
  • fexofenadine (Allegra)
  • diphenhydramine (Benadryl)

Older, first generation antihistamines like Benadryl may be more likely to cause weight gain. Non-sedating antihistamines are probably not linked with significant weight gain.

Antihistamine activity can boost appetite. Studies have shown that some antihistamines may increase weight, body mass index, waist circumference, and insulin levels. For many patients, the allergy benefit with antihistamines outweighs any slight weight gain risk.

Do Antipsychotics Cause Weight Gain?

Many antipsychotics are known for their ability to lead to weight gain. Atypical antipsychotics can lead to changes in metabolism and increase the risk for diabetes and high cholesterol. In a meta-analysis looking at the effect of various drugs on weight, the atypical antipsychotic class was linked with the most weight gain.

Antipsychotic medications are often used for bipolar disorder and schizophrenia, and patients can gain from 7% to 10% of their body weight.

The common atypical antipsychotics

have all been linked to significant weight gain, with clozapine and olanzapine having the highest risk. On average over a 3 month timeframe, weight gains have been reported as:

  • olanzapine (2.4 kg or 5.2 lbs)
  • quetiapine (1.1 kg or 2.4 lbs)
  • risperidone (0.8 kg or 1.8 lbs).

Asenapine (Saphris), iloperidone (Fanapt), paliperidone (Invega), quetiapine (Seroquel), risperidone (Risperdal) are ranked in the middle for weight gain, with aripiprazole (Abilify), lurasidone (Latuda), and ziprasidone (Geodon) having the lowest risk, according to a study by Musil and colleagues.

Certain drugs may also block histamine activity and affect serotonin which may contribute to the mechanism of weight gain. In addition, mental disorders like schizophrenia are known to cause weight gain, as well, and this may be a contributing factor.

Can Antipsychotics Affect Blood Sugar?

Weight gain, diabetes, and increases in lipid levels like cholesterol are the components of metabolic syndrome usually associated with antipsychotics. The mechanism may be from increased appetite or changes in metabolism.

Antipsychotics may impair glucose (blood sugar) control and lead to insulin resistance, impaired glucose tolerance and a higher risk for type 2 diabetes.

  • Second generation antipsychotics such as clozapine (Clozaril) and olanzapine (Zyprexa) are linked with the greatest level of weight gain, blood sugar changes and lipid elevations, relative to other drugs in this class.
  • However, antipsychotics, if prescribed, are a needed treatment of serious mental health conditions such as schizophrenia or bipolar disorder.
  • Talk to your doctor before stopping or changing treatment. Your doctor can assess if a change in treatment is necessary. You may need to engage in extra exercise or diet modification, as well.

Ziprasidone (Geodon) and aripiprazole (Abilify) are more weight neutral antipsychotics, but may still increase blood sugar.

Can Blood Pressure Medications Cause Weight Gain?

Beta-blockers are a frequently used class of drug for blood pressure, and they are affordable, too. However, many beta-blockers are linked with weight gain.

Common examples of this class that may expand the waist include:

  • metoprolol
  • atenolol
  • propranolol

Many of the older beta-blocker drugs may slow down activity in general, which may be responsible for some of the weight gain. Patients may be tired, have lack of energy, and feel fatigued, which may affect their ability to stay active and exercise. This can lower the number of calories burned each day.

Can Corticosteroids Increase Appetite?

Corticosteroids (glucocorticoids) include drugs such as:

  • prednisone
  • betamethasone
  • dexamethasone
  • methylprednisolone
  • triamcinoline
  • hydrocortisone

Corticosteroids are used for multiple conditions, including severe asthma, acute allergies or inflammatory disorders such as arthritis. These drugs can boost the metabolic rate and your appetite, too. High doses and long-term use of these agents may carry a significant risk of weight gain.

Local injectable corticosteroids (for example, used for knee pain) and inhaled corticosteroids used for asthma are not associated with weight gain.

Diabetes Drugs and Weight Gain

Putting on weight is the last thing someone with type 2 diabetes wants to do; it can lead to -- or worsen -- insulin resistance and overall diabetes control.

However, the type 2 diabetes drugs:

  • glyburide (DiaBeta)
  • glipizide (Glucotrol)

are both from an older diabetes drug class and can lead to significant weight gain. These agents may increase insulin production, which can lower blood sugar and increase appetite.

Injectable insulin can also lead to weight gain.

Other drugs used in the treatment of type 2 diabetes, such as the thiazolidinediones -- pioglitazone (Actos) and rosiglitazone (Avandia) -- may also lead to weight gain and fluid (water) retention.

The meglitinides such as nateglinide (Starlix) and repaglinide (Prandin) are also linked with weight increases, roughly 1 kg (2.2 lbs) to 3 kg (6.6 lbs) over a 4 to 6 month study period.

However, many type 2 diabetes treatments are not associated with weight gain, including metformin, usually the first drug of choice for treatment in this group. Other treatments, such as the SGLT-2 inhibitors or the GLP-1 receptor agonists, can also help with weight loss.

Which Diabetes Drugs Are Less Likely to Cause Weight Gain?

Luckily, there are several diabetes medications that may not add on unwanted pounds.

Metformin (Glucophage) and sitagliptin (Januvia), type 2 diabetes drugs, may either not affect weight or be associated with weight loss. However, a recent meta-analysis did find a slight weight increase (~0.5 kg or 1.1 lb) with sitagliptin.

Glucagon-like peptide-1 (GLP-1) receptor agonists slow digestion in the stomach, but can lead to nausea and vomiting. They are given by injection. These drugs have been shown to lead to modest weight loss, even in patients without diabetes. However, the 3 brands listed below are not specifically approved for weight loss.

Saxenda is the brand name of liraglutide approved to help with weight loss, along with diet and exercise, but is not used in treating type 1 or type 2 diabetes. Be sure you do not use Saxenda and Victoza together.

The alpha-glucosidase inhibitors miglitol (Glyset) and acarbose (Precose) were shown to be linked with a 0.7 kg (1.5 lb) and 0.4 kg (0.9 lb) weight loss, respectively, in a meta-analysis evaluating weight changes with medications. These drugs may help with a modest weight loss in patients with diabetes.

Pramlintide (Smylin), an amylin analog, has also been reported to lead to a weight loss of 2.3 kg (5 lb) in a large meta-analysis from Domecq and colleagues. Amylin analogs help control blood sugar by inhibiting glucagon secretion, delaying gastric emptying, and signaling the feeling of fullness, which suppresses the intake of food.

Seizure Drugs and Mood Stabilizers Can Add Pounds

Drugs for seizures and bipolar disorder are important medications for serious conditions, and patients should discuss the issue of weight gain with their doctor before stopping or changing any medications.

Valproic acid (Depakote, Depakene) is used to treat epilepsy (seizures) and bipolar disorder, and is also used for migraine prevention. Valproic acid appears to boost appetite and may result in a 4.5 kg (10 lb) or more weight gain.

A meta-analysis showed that gabapentin (Neurontin, Gralise) was associated with a weight gain of 2.2 kg (4.8 lbs) after 1.5 months of use.

Lithium and lamotrigine were not associated with a statistically significant effect on weight; therefore, they may be weight neutral.

However, in the same meta-analysis from Domecq, significant weight loss was noted with zonisamide (Zonegran) of 7.7 kg (17 lbs), an anti-convulsant drug, and topiramate (Topamax) of 3.8 kg (8.4 lbs), used for seizures and for migraine prevention.

What Should I Do If I Think My Medication Is Causing Weight Gain?

If your weight increases after starting a medication, talk to your doctor about the benefits and risks of using the drug, and if it's been shown to be linked with weight gain in clincial studies.

If a change in your medication is needed, there may be another drug your doctor can prescribe -- maybe even in the same class of drug -- that will work just as well, but not increase your weight. Have your doctor and pharmacist review your other medications for weight-related changes.

It may also be that medicine is not the cause of the weight gain. Consider your diet and exercise routine, and speak with a dietician if needed. Your doctor can give you advice on how to control the weight, including exercise and diet tips.

Finished: Can Prescription Drugs Lead to Weight Gain?

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Further information

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