Almost everyone experiences a sexual problem at some time or other, sex therapists say. While most are resolved without professional help, others may persist or intensify and require assistance.

What qualifies as a sex problem, and how do you know when it's time to seek help? There are few absolute answers, experts say, but there are some general guidelines.

Seeking help could improve more than your sex life, since sexual problems can be important warning signs of some physical or emotional illnesses, including depression.

Before beginning therapy, have a thorough physical exam to rule out a medical illness that could be causing or contributing to a problem.

In general, consider consulting a sex therapist if you or your partner find that: Sex is physically uncomfortable or painful. You are having sex less and less frequently. You have a general fear of sex or feeling of revulsion about sex. Sexual pleasure is declining. You experience decreasing desire for sex. Sexual problems seem to persist for several months or increase in frequency. These can range from a male's impotence to a female's difficulty in achieving an orgasm.

"We are all susceptible to things like fatigue, indigestion and stress from work," says Dr. Robert C. Kolodny, medical director of the Behavioral Medicine Institute in New Canaan, Conn. "Those short-lived transient problems are not something that should send someone scurrying off to a sex therapist. But on the other hand, if a sex problem is persistent, meaning that it lasts for a month or more, you might look at the reasons why the problem is there."