In the last few years, the abuse of crystal methamphetamine (also known as crystal, meth, tina or speed) has gotten out of control in the U.S. gay community. One reason this is so alarming is that the abuse of crystal meth contributes to the spread of HIV infection.

Crystal meth is similar to pure amphetamine and ephedrine. It is easy to get, costs less than cocaine and is highly addictive. Crystal meth can be smoked, injected, snorted and swallowed.

Like all amphetamines, crystal meth causes large amounts of dopamine to be released in the brain. Dopamine is a chemical that improves mood, increases self-confidence and strength and heightens sex drive. Unlike other amphetamines, crystal meth works mainly on the brain, causing fewer side effects on other parts of the body (such as rapid heart rate and shortness of breath).

The problem with frequent use is that people need larger amounts to get high. At higher doses, side effects on other parts of the body become more obvious. At very high doses, usually taken by accident, people can develop brain-damaging fevers, stroke-producing high blood pressure, heart attacks and massive damage to muscle tissue that can lead to kidney failure and death.

Long-term use changes the chemical balance of the brain and can cause a mental illness called psychosis. In the psychotic state, hallucinations are common. People may believe they are infested with parasites, which they see crawling from their nails or out of their skin. They come to the doctor's office with sores caused by picking and scratching. If the drug is not stopped at this point, the person may wind up in the psychiatric ward unable to take care of him or herself.

Long-term users of crystal meth experience withdrawal when they stop the drug. Withdrawal symptoms include fatigue, depressed mood, loss of pleasurable feelings and suicidal thoughts. These symptoms may never go away, even if the person never uses crystal meth again.

One of the worst effects of crystal meth is that users often have unprotected sex when they are high. This puts people at risk for new HIV infections. Even people who already have HIV can get reinfected with a drug-resistant strain of HIV or contract another sexually-transmitted disease.

In addition, crystal meth may interact with HIV medications. There is one report of a person taking a protease inhibitor who died of a crystal meth overdose because of a drug interaction.

Successful treatment of crystal meth addiction is difficult because most people start using again. Nevertheless, it's worth seeking counseling rather than trying to stop the drug on your own. Most cities have drug addiction treatment programs.

Your best bet is not to start using crystal meth in the first place. But if you have, seek help to kick the habit. Call the National Clearinghouse for Alcohol and Drug Information at 800-729-6686 for treatment programs in your area.

Ross Slotten is a family physician in Chicago who has specialized in the treatment of HIV+ people for 20 years.