When is stress normal, and when is it extreme enough to warrant medication? Panic attacks or worry so intense that it interferes with daily functioning means it's time to talk to a doctor, says Valerie Davis Raskin, M.D., author of When Words Are Not Enough. If meds are in order, she says, the next question is whether to take a drug every day or only when you feel symptoms.

Daily Use
If you're anxious all the time, selective serotonin reuptake inhibitors (SSRIs), including Prozac, Zoloft and Paxil, may be the best choice. Technically, SSRIs are antidepressants, though they're often prescribed in smaller doses to treat anxiety. They have to be taken every day, sometimes twice a day, and you won't feel them working for a few weeks. Many users may feel jittery or have trouble sleeping at the beginning of treatment and should talk to their doctors about adjusting dosages. Raskin estimates that at least 30 percent of women experience some change in sex drive.

The drug BuSpar (generic name: buspirone) is chemically similar to the SSRIs, but the FDA has approved it only for treating generalized anxiety disorder—the state of feeling uncontrollably edgy all the time. (It isn't effective for panic attacks, which come and go.) Like an SSRI, it has to be taken every day, usually twice a day.

Occasional Use
Beta-blockers are best for people with event-related anxiety, like extreme stage fright. These drugs block physical symptoms (rapid heart rate, sweating, tightness in the chest) without affecting mental function or dulling anxious thoughts. Inderal (generic name: propranolol) is the beta-blocker most often used to treat event-related anxiety. Its side effects include weakness and cold hands and feet.

Benzodiazepines, a class of drug most specifically used to treat anxiety disorders, should be taken only when you feel you need them. They can become addictive. Benzodiazepines act as sedatives on the nervous system, so they usually make people sleepy—you shouldn't drive when taking them and you should avoid drinking. The four most common are:

• Xanax (generic name: alprazolam): Usually works within 20 minutes, making it particularly useful for treating panic attacks and phobias. Because of this quick rush, most doctors feel Xanax is the most addictive benzodiazepine.
• Ativan (generic name: lorazepam): Usually works in an hour. Doesn't affect the liver as much as other benzodiazepines—important for patients taking the Pill, cholesterol or ulcer medications, or other drugs that may affect the liver.
• Klonopin (generic name: clonazepam): Lasts longer in the body and is therefore more sedating than Xanax or Ativan. Users may feel groggy that day, hungover the next. As with all benzodiazepines, enjoyment of or dependence on this feeling of sedation is a warning sign of addiction.
• Klonopin (generic name: clonazepam): Lasts longer in the body and is therefore more sedating than Xanax or Ativan. Users may feel groggy that day, hungover the next. As with all benzodiazepines, enjoyment of or dependence on this feeling of sedation is a warning sign of addiction.