Although antiretroviral therapy (ART) has transformed HIV infection from a universally fatal disease into a chronic condition that can be managed, it’s still a lifelong and incurable infection. Most people would prefer to avoid being infected with the virus. There are a number of common myths and misconceptions about how HIV can be transmitted, which can make it difficult to know how to keep yourself safe.
Here are answers to some common questions about how HIV is transmitted.
HIV is actually a very delicate virus. Even though it’s extremely rare for the human body to get rid of it entirely, this virus can’t really live outside of the human body. The exception to this would be if an infectious fluid (blood, sexual fluids, or breastmilk) is somehow stored under the right conditions to keep the virus alive; in this case, HIV may be able to survive in the fluid for weeks. However, this is very uncommon under normal circumstances.
Studies have shown that once HIV is placed on a surface outside of a human body, most of the particles of the virus are destroyed very quickly. The virus loses most of its ability to cause an infection within a few hours. This is what happens when very large amounts of the virus are placed on a surface. In general, under normal conditions, there won’t be nearly as much of the virus present on a given surface as in these studies, and whatever small amounts of virus may be present will be neutralized very quickly.
There are no known cases of a person getting HIV from transmission on a surface, such as a toilet seat, doorknob, or dish. Even for people who live with HIV-positive family members or partners, there’s no need to worry about getting HIV from touching surfaces. The virus is too delicate to survive on surfaces for very long. Additionally, there are infectious amounts of the virus present only in specific body fluids – blood, sexual fluids, and breastmilk. Generally, an HIV-positive person won’t be shedding virus onto household surfaces.
HIV also can’t live in water. It can’t be transmitted in a pool, even if the pool water isn’t chlorinated. Even sharing dishes with an HIV-positive person is considered to be safe.
Similarly, HIV can’t be transmitted through food. In fact, there have been no documented cases of transmission of HIV through sharing food or drinks with an infected person. Although an HIV-positive person may have tiny amounts of the virus in their saliva, this isn’t enough to transmit the infection.
HIV can certainly be transmitted through blood. However, once the blood dries out, the virus dies very quickly. Because of this, dried blood generally can’t transmit HIV. However, if the blood is still wet, then HIV could still be present.
Once the blood on the needle has dried out completely, the virus will not survive for very long. However, if there are still drops of blood on the needle, then transmission of HIV on needles is possible. Even very tiny drops of blood that are too small to see may harbor the virus. This is why transmission of HIV is definitely known to occur through sharing needles or other drug injection equipment.
Inside of a used needle, blood can take a long time to dry out. Some studies have found that HIV can remain infectious in syringes filled with blood for over a month, if they’re kept under the right conditions. Although this is not particularly likely to occur, it’s best to consider any used needle or syringe to be potentially infectious, and to dispose of it safely. Sharing needles with someone else, even if you wait a while in between people, is not safe.
With a knife, HIV should not be able to survive for as long as inside of a needle, because it will dry out faster. However, if the same knife has contact with two different people’s blood in a short space of time (such as might occur during certain types of blood play), then HIV could possibly be transmitted. For safety, it’s better to clean the knife (with soap and water or rubbing alcohol) between its use on different people, or use a different knife for each person.
Just like on other types of surfaces, HIV doesn’t survive for very long on dental instruments. However, dental instruments and other medical instruments are sterilized very thoroughly in between patients. This is important, because while HIV can’t live for long on these instruments, there are some viruses that can. Because of this, healthcare providers clean instruments extremely thoroughly in between patients, in order to ensure that no pathogens are transmitted. You don’t have to worry about getting HIV from your dental care or other types of medical care.
In general, HIV isn’t transmitted on clothing. The virus is not present on an infected person’s skin and can’t be transmitted through their sweat, so it generally won’t even make it onto their clothing. If it did, it wouldn’t survive for long because it would dry out.
The only reason to worry about an HIV-positive person’s clothing is if there’s blood, sexual fluids, or breastmilk on it, and even then, the virus could only be transmitted if this fluid gets on someone else’s broken skin (like a cut) while the fluid is still wet.
In general, HIV doesn’t survive for very long when exposed to air. Once a surface dries out, the virus won’t last for very long.
Many people don’t realize that they have HIV. The virus often doesn’t cause any noticeable symptoms until fairly late in the course of the infection. In order to know if you have HIV, the only way is to take a blood test. This can be done at home, with the blood sample obtained through a small fingerprick.
Abdala N, Reyes R, et al. Survival of HIV-1 in syringes: effects of temperature during storage. Subst Use Misuse 2000 Aug;35(10):1369-83. doi: 10.3109/10826080009148220.
HIV/AIDS. Mayo Clinic. https://www.mayoclinic.org/diseases-conditions/hiv-aids/symptoms-causes/syc-20373524. Accessed 20 April 2022.
HIV and AIDS. National Health Service. https://www.nhs.uk/conditions/hiv-and-aids/. Accessed 20 April 2022.
HIV Transmission. Centers for Disease Control and Prevention. https://www.cdc.gov/hiv/basics/transmission.html. Accessed 20 April 2022.
Transmission of HIV/AIDS. Stanford Medical School. https://stanfordhealthcare.org/medical-conditions/sexual-and-reproductive-health/hiv-aids/causes.html. Accessed 20 April 2022.