Forbes logoEver experience a sudden, strong desire to gamble, or a funny feeling that you've been driving in your sleep?

It could be nothing. Or maybe it's time to finally read the warnings that came with that bottle of over-the-counter or prescription drugs you're taking. Strange as it may sound, compulsive gambling and sleep-driving are two real side effects that have been reported by patients or drug manufacturers in recent years.

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In recent months, popular new anti-smoking treatment Chantix has made headlines for its array of potential side effects, which include insomnia and nightmares. In February, the U.S. Food and Drug Administration announced that Pfizer, the manufacturer of Chantix, had updated the drug's prescribing information to include additional warnings about the possibility of severe changes in mood and behavior in patients taking it.

Last year, over-the-counter diet drug Alli made waves. Late-night talk show hosts in particular had a field day joking about the product's warning label, which included a recommendation to wear dark pants and bring a change of clothes to work until users had a sense for the drug's gastrointestinal effects.

Even though drugs must pass through three phases of clinical studies before getting FDA approval, new side effects often emerge only once a medicine reaches the broader population, says Cynthia Reilly, director of clinical standards and quality for the American Society of Health-System Pharmacists.

FDA officials confirmed last week that the agency is launching a plan to strengthen oversight of prescription drugs after they are approved, including a new database of medications' possible side effects, and timelines for following up on those concerns.

But in the meantime, how much attention should consumers pay to news of strange side effects?

The answer, experts say, is plenty. "People really need to be aware of all [a drug's] side effects, strange or not," says Reilly.

That means actually reading the drug's label, as well as those papers that come stapled to your prescription bag at the pharmacy. No one--not your family members, not your assistant, not even your doctor, is going to recognize changes in your health as quickly as you can. And left ignored, some side effects can cause permanent damage.

Pharmacy handouts and data cribbed from vetted Internet sources may be your best bets for getting more information about side effects, since TV drug ads don't devote much time to them. A new University of Georgia study found that the average 60-second prescription drug ad aired on broadcast and cable television contained less than eight seconds of side effect disclaimers, and the average 30-second ad had less than 4.4 seconds. Most 15-second ads studied devoted no time at all.

When researching potential hazards, be careful not to lose perspective. While it is important to acquaint yourself with all of a drugs' side effects, only some are worth really worrying about, such as an increased likelihood of suicide, says Dr. Darrell Abernethy, chief science officer for the United States Pharmacopeia, a private, non-profit, standards-setting organization that promotes the safe use of medications. Other side effects, like the temporary loss of sense of taste often associated with hypertension treating ACE inhibitors, aren't as big a deal.

Experts suggest making a quick call to your doctor when you hear about side effects associated with a drug you've been taking. That will help you figure out how common the side effects really are, and evaluate alternative treatments.

"People need a medical home," says Dr. Peter Lund, president of the Pennsylvania Medical Society and founder of the organization's Institute For Good Medicine. "They need to have a health care provider or doctor to turn to with those questions."

Just keep in mind that a doctor might weigh a drug's side effects differently than you would. "You have to make your own choice about how you want to proceed," says Abernethy.