Can you get HIV if have a mouth ulcer and kiss someone infected who ulcers?

It is highly unlikely to contract HIV through kissing, even if both partners have mouth ulcers. HIV is primarily transmitted through unprotected sex, sharing needles or other drug paraphernalia, and from an infected mother to her child during pregnancy, childbirth, or breastfeeding. The amount of HIV present in saliva is extremely low, and even if there is some contact between saliva and an open wound, the risk of transmission is still very low.