Should I be worried about HIV AIDS if bought a pair of underwear with small spot blood on them the first time used them?

The risk of contracting HIV from contact with a small spot of blood on a pair of underwear is extremely low, bordering on non-existent. HIV is primarily transmitted through unprotected sex, sharing needles, or contact with infected blood or bodily fluids.

The virus is fragile and does not survive well outside the human body. it becomes inactive quickly when exposed to air or dry surfaces. To acquire HIV, a significant amount of infected blood or bodily fluid needs to enter your bloodstream, which is unlikely to happen from a small spot of blood on used underwear.