The drugs that treat HIV have extended people’s lives so that an HIV diagnosis is no longer a death sentence. But while they suppress HIV, many of the meds also cause side effects that can make life difficult. A common complaint: diarrhea.

Enter the dragon—or, more accurately, the extract of a plant called sangre de grado, or dragon’s blood.

The experimental drug crofelemer, made from this plant, has proved effective at controlling diarrhea. Crofelemer is now in Phase III clinical trials, moving toward FDA approval.

Healing such side effects does more than make people’s lives more comfortable. It also helps them take all of their HIV drug doses—crucial, because missing doses can let the virus mutate and become resistant to the meds.