Getting fat: Should you blame your meds?

What drugs are known to cause weight gain?
If you’re not eating more or exercising less but you’re still gaining weight, your medication may be responsible. Here are some drugs and drug classes that are known to have weight gain as a side effect.

• Antidepressants
• Antipsychotics
• Anti-seizure drugs
• Anti-migraine
• Diabetes drugs
• Blood pressure agents
• Anti-inflammatory (steroids)
• Hormone therapy (like tamoxifen)
• Antihistamine

Antidepressants
Some years ago, I did some studies that showed that tricyclic antidepressants (like Elavil and Tofranil) caused a drop in metabolic rate of up to 10 percent. Translated into calories, this is a pound every seven to 10 days, if you don’t change your diet. These older types of antidepressants affect neurotransmitters, causing a broad range of side effects including significant weight gain. Newer antidepressants don’t have the same side effect. While Paxil and Zoloft do cause some weight gain, other SSRIs, like Prozac, Celexa and Lexapro, don’t. For Paxil and Zoloft, the weight gain can add up to five to 40 pounds a year. Some people do experience weight gain with Lexapro or Celexa, but most don’t. In this case, it is not a surprise to have idiosyncratic responses, since the chemical structure of all the SSRIs is so similar.

Newer drugs, such as serotonin-norepinephrine reuptake inhibitors (SNRIs), don’t appear to have weight gain as a side effect. In fact, Meridia, a weight-loss drug, is an SNRI. Another SNRI, Effexor, has no weight-loss properties, but it is an antidepressant. This shows that tiny changes in chemical structure can have big effects on the brain.

Antipsychotic drugs and other mood stabilizers
Patients who have bipolar disorder, schizophrenia or other psychotic disorders may be prescribed Zyprexa (olanzapine) or Risperdal. Both drugs are associated with weight gain, but they are better than older ones, such as Haldol. While they all cause some weight gain, the new ones are not as sedative. These drugs stimulate appetite and may slow down the patient’s metabolic rate.

Lithium is well known for causing weight gain: One-third to two-thirds of patients who take this drug experience weight gain. It increases appetite, slows metabolism, and increases fluid retention. (While water weight isn’t true weight gain, it makes the patient feel bloated and fatter.) Patients on lithium can gain 20 to 30 pounds — or even more — in a year.

Anti-seizure drugs
A common anti-seize medication, Depakote (valproate) can cause a patient to gain up to 60 pounds in a year. A newer drug, Topamax (topirimate), has a different side effect — weight loss. This can be a problem for patients who need to maintain their weight, or even gain a few pounds to stay healthy.

Anti-migraine medication
Weight gain can be a side effect in the beginning.

Antihistamine
Weight gain can occur some times.

Beta blockers
Drugs to control blood pressure, such as Atenolol, can sometimes cause weight gain.

Steroids
Steroids include such drugs as glucocorticoids and cortisone. For patients who need to take these drugs for the long-term treatment of rheumatoid arthritis or chronic inflammation, they can gain as much as 100 pounds in a year. Patients report that they have increased hunger on steroids. While it is likely that these drugs also affect metabolism, it is not known exactly how. Even transplant patients taking anti-rejection drugs (anti-inflammatory drugs) seem to experience some weight gain.  

Insulin and other diabetic drugs
Insulin is a “fat sparing” hormone, so the body tends to gain weight with insulin or insulin promoters (like Actos). In contrast, for those with early type 2 diabetes, or metabolic syndrome, Glucophage (metformin) seems to help with weight loss. Many diabetics try to lose weight, so they won’t have to take either Actos or insulin. Patients who do take these drugs can gain 40 pounds in a year.

Remember, if you suspect that you’re adding extra pounds, don’t stop taking your medication. Call your doctor, and ask her if there is another drug you could take instead.

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