These fears aren’t supported by scientific evidence. HIV needs certain unlikely conditions to survive outside of the human body.

This article looks at the HIV virus and how long it can survive outside the body. It also looks at whether you can get HIV from this type of exposure.

Assessing the Risk of HIV Infection

Under certain conditions, HIV can survive outside of the body for hours or even days. The conditions have to be just right, though. 

To survive, HIV needs the right:

Temperature. Humidity. This measures how much moisture there is in the environment. UV exposure. This is exposure to the ultraviolet radiation in sunlight. pH balance. This measures how acidic the environment is.

This is a very unusual set of conditions. Still, it is possible.

To understand this. you need to know the difference between perceived risk and documented risk.

Perceived vs. Documented Risk

Perceived risk is also called theoretical risk. It is based on belief rather than fact. It persists even though an event is unlikely to ever occur.

Documented or actual risk is based on evidence that something might actually happen. 

Perceived risk is about theory. Documented risk is about fact.

With HIV, the potential to infect isn’t actual risk unless four specific conditions are met:

There must be body fluids in which HIV can thrive. This includes semen, blood, vaginal fluid, and breast milk. HIV cannot thrive in places with high acidity. This includes the stomach and the bladder. There must be a route by which HIV can enter the body. This includes sexual intercourse and shared needles. Rarely, occupational exposure may happen. This is where HIV is transmitted from patient to healthcare worker. Vertical transmission is when HIV is passed from mother to child. The virus must be able to reach vulnerable cells inside the body. This requires a significant break in the skin or deep penetration of the skin. The virus can also be absorbed through the tissues of the vagina or anus. Scrapes, abrasions, and skin pricks are not deep enough for an infection to occur. HIV cannot pass through intact skin. There must be enough virus in the body fluids. Saliva, sweat, and tears don’t transmit HIV. They either contain enzymes that inhibit HIV or have a pH hostile to HIV.

Unless all of these conditions are satisfied, an HIV infection simply cannot occur.

Conditions HIV Needs to Survive

HIV could only survive outside the body under these specific conditions:

Colder temperatures: Outside the body, temperatures below 39 degrees F are ideal for HIV. HIV does not do well at room temperature, or around 68 degrees F. It continues to decline as it reaches and goes beyond body temperature, or 98. 6 degrees F. Ideal pH: The ideal pH level for HIV is between 7. 0 and 8. 0. A perfect pH for HIV is 7. 1. The virus can’t survive pH levels above or below that. Dried blood: HIV can survive in dried blood at room temperature for up to six days. The concentrations of virus in dried blood are typically low to negligible, though. No UV exposure: HIV survives longer when is not exposed to ultraviolet (UV) radiation. UV light quickly degrades viral DNA. It also degrades the lipids that make up the virus’ shell. This makes it incapable of attaching to other cells and infecting them.

It is technically possible for HIV to survive outside of the body if these conditions are met. Still, infection under these circumstances is very unlikely. So far there have been no documented cases of someone getting infected from a discarded syringe in a public place.

In 2015, the Centers for Disease Control and Prevention confirmed only one needlestick infection since 1999. That case involved a lab researcher working with live HIV.

Getting body fluids or saliva in the eye is also an extremely unlikely way to transmit the HIV virus.

Post-Exposure HIV Prevention

It is not known how much body fluid is necessary for an HIV infection to happen. It is also not known how big a wound needs to be. If in doubt, it’s always better to be safe. Go to your nearest emergency room or walk-in clinic.

If you have ongoing fears about HIV, consider meeting with a specialist. An HIV specialist, psychologist, or trained counselor can help.

This is important if your fears are getting in the way of your relationships or quality of life. There are treatments available to help control your anxiety. This can help improve your overall sense of wellbeing.

Summary

In order for HIV to live outside the human body, it has to have the right temperature, humidity, pH, and UV exposure. The right circumstances are very uncommon.

So far, there have been no documented cases of HIV transmission happening after contact with a discarded needle.

If you are concerned about possible exposure to HIV, go to the ER or a walk-in clinic. There is post-exposure treatment available that can help prevent infection.

If your worries get in the way of your relationships or quality of life, there are specialists who can help you control your anxiety.

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