If you are packing on extra pounds despite eating well and exercising, your medication may be to blame. Experts say this unwelcome side effect of certain prescription drugs may exacerbate the condition they are meant to treat. For example, individuals with high blood pressure or arthritis are advised to maintain a healthy weight yet common prescriptions drugs to treat these illnesses often cause weight gain. According to a recent study published in Obesity, one in five adults takes at least one medication that causes weight gain.

According to AARP, the most common culprits are beta-blockers taken to lower blood pressure and diabetes drugs. Be aware if you take one of these medications:

1. Diabetes drugs. People with type 2 diabetes are advised to maintain a healthy weight, but some medication to treat the condition can result in weight gain. Injectable insulin is one that can cause a spike in weight. The drug helps cells absorb glucose but when too much glucose is the result, it is converted to fat. Sulfonylureas reduce blood sugar levels by 20%, but they can also cause a four to five-pound weight gain, according to one study. Speak with your doctor about taking an alternative medication is right for you.
2. Beta-Blockers. These drugs are commonly used to treat hypertension, says Aaron Emmel, PharmD, the founder of PharmacyTechScholar.com. Some are more likely to cause weight gain, including Tenormin and Lopressor, says Everyday Health. Emmel believes that the weight gain may be caused by fatigue, a side effect of the drug, which can decrease your exercise tolerance. The drug may slow metabolism, too, according to a study published in the journal Gastroenterology. The researchers suggested that people who are obese or overweight should ask their doctor for a different first-line medication to treat high blood pressure.
3. SSRIs. Selective serotonin reuptake inhibitors treat depression by increasing the level of the neurotransmitter serotonin in the brain. Some examples include Lexapro, Paxil, and Zoloft. Researchers believe the drugs may alter metabolism or lead to an increased appetite. “If you experience weight gain, talk to your physician,” Emmel advises.
4. Corticosteroids. Oral corticosteroids, such as prednisone, treat a wide range of illnesses, from asthma to arthritis. “These have a lot of side effects,” says Ashley Ellis, PharmD, including increased appetite, fluid retention and altered metabolism. Staying at a healthy weight is important for people with arthritis, so taking these medications with food such as almonds or yogurt may help reduce side effects. Usually, corticosteroids are prescribed for short-term use, so their side effects are limited, however if you are taking these drugs long-term, be diligent with diet and exercise.
5. Migraine medications. Weight gain is a side effect of some migraine prevention drugs, such as Inderal and Depakote. This creates a vicious cycle as extra weight increases the risk for more frequent and severe migraines, says AARP. According to the American Migraine Foundation, individuals at a healthy weight have a 3% chance of developing chronic headaches, while those who are overweight have three to five times that risk. Ask your doctor about switching to one that may suppress appetite, such as Topamax or Zonegran.