PCP stands for pneumocystis carinii pneumonia. This serious infection mainly affects the lungs, but it can also affect other organs, including the skin. Without preventive medication, over 80% of people with HIV will likely get PCP. Early signs of PCP are trouble breathing, having a fever, and dry coughing. PCP can usually be treated with one of several different medications, including TMP/SMX (trade name Bactrim or Septra), pentamidine, trimetrexate and atovaquone (trade name Mepron). However, it's much better to avoid getting PCP in the first place.

Studies have shown that PCP can be prevented. People with under 200 T4 cells are most at risk to get PCP, but other HIV+ people can get it as well. Anyone who is HIV+ should talk to their doctor about preventing PCP.

There are several different medications to prevent PCP. The main one is called Bactrim or Septra (TMP/SMX). Studies so far show that this is the most effective drug for preventing PCP. It also helps prevent another common infection called toxoplasmosis.

Not everyone can take TMP/SMX because of side effects. Around 50% of people have allergies to TMP/SMX because it contains a substance called sulfa. Signs of an allergic reaction can be skin rashes and fever. If you are starting on TMP/SMX and experience any symptoms, report them to your healthcare provider immediately - in rare cases they can be a sign of a dangerous allergy called Stevens-Johnson Syndrome.

Recent studies have found that many people can take TMP/SMX even if they have an allergy at first. A procedure called desensitization, where you build up the dose slowly, can help the body get used to the drug. The Network has several commonly used desensitization protocols in our treatment library, call if you need a copy.

When TMP/SMX was first used, the standard dose was one double-strength tablet every day. Several recent studies have found that one double-strength tablet taken three times a week is just as effective, and causes less side effects. Most doctors now use this less frequent dose when they prescribe TMP/SMX.

If you can't take Bactrim or Septra, you may be able to take dapsone. Dapsone is an antibiotic similar to TMP/SMX, but it has less sulfa in it. Although it has not been studied as much as TMP/SMX, early results show that it is probably just as effective in preventing PCP. Dapsone may also be effective at preventing toxoplasmosis. Until this is known for certain, some doctors prescribe a drug called pyrimethamine along with dapsone if a person is at risk for toxoplasmosis.

Another preventive medication for PCP is aerosolized pentamidine. Aerosolized pentamidine is a form of drug you breath through a special mask. The procedure takes 30-45 minutes and is done once every four weeks. This drug does not seem quite as effective at preventing PCP as TMP/SMX and dapsone. Also, it does not offer any protection against toxoplasmosis.

Newer drugs are under study for the prevention of PCP. Atovaquone (trade name Mepron) is being compared to aerosolized pentamidine in one study. There are also several studies enrolling that are looking at ways to help people take TMP/SMX. Call The Network for more information about these studies.

Side effects:
TMP/SMX can, more rarely, have side effects other than allergic reaction. These can include minor fevers, nausea, low white blood cells, low platelets, and liver irritation. Dapsone contains less sulfa, although there is still the risk of allergic reaction similar to TMP/SMX. Dapsone has also been associated with mild nausea, fever, low white and red blood cells and liver problems. Aerosolized pentamidine can cause cough, dry throat, bad taste in the mouth, lung spasms, anxiety, headache and chills.

Patient assistance programs:

• Bactrim
• atovaquone

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