HIV transmissions as a result of one person's blood entering another person's open sore or wound are theoretically possible, but in practice hardly ever happen. Only a handful of cases have ever been documented.
Assessing the Risk
It's true that if an HIV-positive person's blood enters the bloodstream of another person, HIV may be passed on. For example, this often happens when syringes and needles used to inject drugs are shared. Transmission following limited contact -- for example, blood touching an open sore -- is much less likely.
If you are concerned about an incident in which you had contact with another person's blood, it's worth noting a few points:
- If the blood came into contact with undamaged, unbroken skin, there is no HIV risk whatsoever.
- HIV is not transmitted through surface scratches, such as paper cuts.
- A cut or wound that is in the process of healing and scabbing over is unlikely to allow entry of the other person's blood.
- HIV does not survive long outside the body, so the risk from blood left behind on objects is minimal.
- The handful of documented cases of HIV transmission involving fights or accidents have involved serious injuries and profuse bleeding.
It's also worth asking yourself if you have any reason to believe that the person who shed the blood is living with HIV.
More on HIV Transmission Risks at TheBody.com
Our Q&A experts sometimes address questions about open wounds and transmission in our "Ask the Experts" forums. Here are some of those questions and our experts' responses:
- Bloody toilet seat
I lifted a public toilet seat with my foot and saw that there was blood underneath. I had a fresh wound on my foot! Could I be at risk for HIV?
- Non-bleeding finger wound
I helped a friend who was bleeding. My middle finger had an eight-hour-old cut on it at the time. What's my HIV risk?
- HIV from a fist bump?
I scratched my knuckle, and then bumped fists with an HIV-positive man who also had scratched his hands.