You probably assume that when your doctor prescribes a medication, the Food and Drug Administration has approved it for your specific condition. But sometimes doctors prescribe drugs to treat conditions other than the ones for which they were approved.

Such “off-label” use, although legal, might not be a good first-choice treatment. Yet about one in five prescriptions are written for an unapproved use. An analysis by Consumer Reports Best Buy Drugs and the American Society of Health-System Pharmacists has evaluated some of the drugs most often prescribed off-label.

The bad news is that the use of drugs in an off-label way is often questionable; almost 80 percent of such prescriptions lack strong scientific backing, according to a 2012 study in the Archives of Internal Medicine. What’s more, some doctors prescribe drugs for a condition without realizing that they’re not intended for that use, says G. Caleb Alexander, co-director of the Johns Hopkins Center for Drug Safety and Effectiveness, and that’s worrisome, too.

A 2009 survey of some 1,200 primary-care physicians and psychiatrists by Alexander and colleagues found that many doctors thought that some common drug treatments were FDA-approved when in fact they weren’t — and that there was little evidence to support their off-label use. “That’s particularly of concern where drugs may have specific, noteworthy safety concerns,” Alexander says.

But taking medication that has been prescribed off-label might have an upside, especially when approved treatments aren’t effective. And there are off-label uses that studies have found to be effective. For example, topiramate (Topamax and generic), a drug approved to treat seizures, also works for treating alcohol dependence.

Some doctors prescribe drugs for a condition without realizing that they’re not intended for that use. (Bigstock)

So how do you know if a prescribed drug is being used off-label? First, ask if it has been approved by the FDA to treat your condition. (You can also check at If the answer is no, ask why it’s being prescribed and whether it is as safe and effective as an approved drug. Also ask about the strength of the evidence to support the off-label use and about alternatives.

And make sure your insurance will cover the cost. Some insurers will want to see evidence that the drug works before they will cover it. Or they might require proof that a standard treatment didn’t work for you.

Some drugs prescribed off-label are known to work well, but others may disappoint or do harm. Here are some common prescription drugs written for unapproved uses and our advice on whether they’re worth taking.

Drugs that may work off-label:

Propranolol (Inderal)

Approved use: High blood pressure

Off-label use: Stage fright

Note: May reduce the physical symptoms of stage fright, such as dry mouth and shaky hands. Side effects can include lethargy, depression, hallucinations, dizziness, low blood pressure and sleep problems.

Bevacizumab (Avastin)

Approved use: Various cancers

Off-label use: Wet age-related macular degeneration

Note: There’s good evidence that it helps, and Medicare usually covers it. Risks may include eye infection, retinal detachment, bleeding and increased eye pressure. More serious side effects have been seen in cancer patients taking a higher dose.

Amitriptyline (Elavil)

Approved use: Depression

Off-label uses: Fibromyalgia, migraine prevention

Note: There’s good evidence that it helps reduce fibromyalgia pain and migraine frequency. Side effects include drowsiness, weight gain, dry mouth and constipation. More serious side effects have been seen in people taking it in higher doses for depression.

Drugs used off-label that you can skip:

Antipsychotics Aripiprazole (Abilify), quetiapine (Seroquel), risperidone (Risperdal)

Approved use: Bipolar disorder, schizophrenia

Off-label use: Agitation, aggression, hallucinations in those with Alzheimer’s disease or other forms of dementia

Note: Poses substantial risks, including death in older patients, Type 2 diabetes, movement disorders, pneumonia, stroke and weight gain. The FDA has warned against using the drugs for those purposes.

Quinine (Qualaquin)

Approved use: Malaria

Off-label use: Nighttime leg cramps

Note: Serious, life-threatening side effects, such as kidney failure, bleeding and heart problems. Risks outweigh any benefits.

Copyright 2013. Consumers Union of United States Inc.

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