MADISON, Wis. -- How safe are prescription drugs and how carefully are they monitored by the Food and Drug Administration?

Consumer Reports has identified a dozen widely-prescribed drugs that are linked to rare but potentially serious reactions, which were either unidentified or underestimated when the drugs were approved by the government, News 3 reported.

Those drugs should be taken with caution, and in most cases only as a last resort.

The drugs and drug types with undetected or underestimated risks at the time of approval are sold under many names and include:

Celebrex,

a pain reliever

Crestor

for cholesterol

Depo Provera,

the contraceptive

Elidel and Protopic

for eczema

Isotretinoin

for severe acne

Lariam

to prevent malaria

Meridia

for weight loss

Ovide

for head lice

Premarin

and other estrogens to treat symptoms of menopause

Serevent Diskus

for asthma

Zelnorm

for irritable bowel syndrome

Zoloft, Effexor,

and other antidepressants, particularly when prescribed to young people.

"These prescription drugs have legitimate medical uses, but there's also evidence that they carry serious risks. Those risks were underestimated or undetected when the FDA approved them," said Joel Gurin of Consumer Reports.

With most of these drugs, consumer reports says the risks are rare, and a few are not conclusively proven, but they point to weaknesses in the nation's drug-safety system.

"The FDA is short-staffed and has tight deadlines to approve new drugs,” said Gurin. “And then once a drug is on the market, the FDA has only limited power to monitor it for safety."

Consumer Reports said if you have been prescribed one of these drugs, don't stop taking it on your own -- it might be right for you. But be sure to talk to your doctor about the risks and whether there are better options.

For a full list of the drugs and their side effects, visit Consumer Reports and click on the "health and fitness" tab.