How Long Can HIV Live Outside of the Body?

Does Contact with Blood or a Syringe Pose Actual Risk?

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Thomas Marthinsen

The general response to that question—the one that a person is most likely receive from helplines or brochures—is "not long." The standard public health message today will tell us, quite fairly, that HIV is a weak virus and that once exposed to air, it can survive for maybe a few minutes at best.

To some, this may seem like a cursory, or even glib, response. Surely if there are greater quantities of blood or body fluids, then it would stand to reason that HIV could possibly survive for longer than a few minutes, wouldn't it?

The answer to that question, in all fairness, would be "yes."

Under specific conditions, HIV can survive for a far longer period of time, sometimes for hours or even days if the right temperatures, pH balance, light exposure, and humidity are achieved.  It is a very difficult set of conditions but is nevertheless possible.

But does that necessarily mean that a person who comes into contact with spilled blood, semen or body fluids run an actual risk of infection?

The answer to this question is most always "no."

The presence of HIV in spilled or discarded body fluids does not inherently mean that it has the potential to infect. While the conditions may be suitable for HIV to survive in microscopic quantities, transmission requires both significant quantities of HIV and the ability for the viruses to reach specific target cells within the body. Unless those conditions are satisfied, HIV infection simply cannot occur.

Determining the Potential for HIV Transmission

When discussing the potential for HIV transmission, it's important to first establish the four criteria that must occur in order for an infection to take place:

  1. There must be body fluids in which HIV can thrive, such as semen, blood, vaginal fluids or breast milk. HIV cannot thrive in the open air or in parts of the body with high acid content (such as the stomach or bladder).
  1. There must be a route of transmission, such as through certain sexual activities, shared needles, occupational exposure or transmission from mother to child.
  2. There must be a means for the virus to reach vulnerable cells within your body, either through a rupture or penetration of the skin, absorption through vulnerable mucosal tissue, or both. Scrapes, abrasions or pricks on the skin do not generally provide an ample route of entry. HIV cannot penetrate intact skin.
  3. There must be sufficient levels of virus in the body fluids, which is why saliva, sweat, and tears are unlikely sources since the level of virus in these fluids is considered insufficient for infection.

Because casual contact with discarded or spilled body fluids do not generally satisfy these conditions, the likelihood of infection is considered low to negligible.

Even in instances where an individual has come into contact with a discarded syringe—considered to be of potentially higher risk—most research has suggested that the risk of transmission was next to zero. An extensive review conducted in Australia in 2003 reported not one case of HIV or hepatitis C as a result of contact with a discarded needle.

Conditions by Which HIV Can Survive Outside of the Body

If HIV were to survive outside of the body for more than a few minutes, it would need to do so within the following conditions:

  • Colder temperatures below 39oF (4oC) are considered ideal for HIV to thrive in syringes, where it is better able to maintain levels of humidity. By contrast, HIV does not do well at room temperature (68oF/20oC), with viability decreasing significantly as it reaches body temperature (98.6oF/37oC) and beyond.
  • The ideal pH level for HIV is between 7 and 8, with the optimal level of 7.1. Anything above or below these levels is considered unsuitable for survival. This is why HIV is less able to thrive in certain mucosal tissues such as nasal passages or the vaginal tissue of healthy women, as well as in feces, urine or vomit.
  • HIV can survive in dried blood at room temperature for up to six days, although most research shows that concentrations of the virus in dried blood are almost universally low.
  • HIV survives longer when it is not exposed to ultraviolet (UV) light. UV light degrades the lipids that comprise HIV's exterior shell, rendering it incapable to attach to other cells, while it also degrades the genetic material that HIV needs to replicate.

Still, given these parameters, there has yet to be a documented case of infection by way of a discarded needle or syringe in a public place. In fact, the largest retrospective study of 274 Canadian children showed not a single case of HIV transmission following an injury with a discarded needle.

Similarly, there has been no documented case of anyone being infected by spitting (despite the fact that people with HIV been been arrested or imprisoned for doing so), nor has there been anyone infected after accidentally touching or getting body fluids in their eyes.

What To Do If You've Been Exposed to HIV

Clearly, there is no definitive line by which to say how much body fluid or how big of a wound is needed for an HIV infection to occur.

If unsure, it is best to act sooner rather than later, either by contacting an AIDS hotline or visiting your nearest clinic or emergency room. They should be able to advise you about the likelihood of transmission based upon the specific details of your case.

If there is still any doubt, post-exposure prophylaxis (PEP) can be prescribed, ideally within 24-48 hours of exposure, to reduce the risk of infection.

If, however, you are having on-going or irrational fears about HIV, consider meeting with a qualified HIV specialist, a psychologist or a trained counselor. Surfing the net for answers will do little to alleviate these concerns and sometimes make them worse.


Abdala, N.; Reyes, R.; Carney, J.; et al. “Survival of HIV-1 in syringes; effects of temperature during storage.” Substance Use and Misuse. August 2000; 35(10):1369-1383.

Tjøtta, E.; Hungnes, O.; and Grinde, B.  "Survival of HIV-1 activity after disinfection, temperature and pH changes or drying." Journal of Medical Virology. December 1991; 35(4): 223-227.

van Bueren, J.; Simpson, R.; Jacobs. P.; et al. "Survival of human immunodeficiency virus in suspension and dried onto surfaces." Journal of Clinical Microbiology. 1994; 32(2):571.

Papenburg, J;  Blais, D.; Moore, D.; et al. "Pediatric Injuries From Needles Discarded in the Community: Epidemiology and Risk of Seroconversion." Pediatrics. 2008; 122:e487-e492,

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