Skin, your body’s largest organ, can weigh 10 pounds and span half a Ping-Pong table. It’s your first line of defense against germs and holds sweat glands for cooling and fat for padding your bod from shocks. Plus it has all those little nerve endings to let you feeeeeeel. HIVers need the skinny on these three nasties:

Seborrheic dermatitis reddens (often with a whitish scale) oily turf like foreheads, eyebrows and scalps (where it’s a.k.a. dandruff). HIVers—especially with low CD4 counts—get more (and worse) cases than neggies. Antifungal creams like Nizoral treat it; pills from Doc tackle the stubborn cases.

Staph strikes with a red, tender bulge under the skin. Once a hospital dweller, the bug now steps out on the town, cruising gym towels and benches and feasting on skin-to-skin contact. There’s been a rash of these bacterial infections among gay men—especially HIVers and crystal users. And it’s often methicillin-resistant staph aureus (MRSA), which resists penicillin-type meds. Generally no more dangerous or invasive than nonresistant staph, MRSA just requires different meds (your doc will culture suspected staph to choose the right ones). Bactrim often works, but you might need intravenous Vancocin or the new pill Zyvox, which can deplete white blood cells.

Med rashes are often triggered by HIV meds—especially a new combo. Most are harmless and respond to Benadryl, but always tell your doc right away. Those from Viramune or Ziagen may be more dangerous. Through it all, do what HIVers do best: Keep a thick skin.