Many people wonder if they can contract a sexually transmitted infection (STI) from wearing someone else’s underwear. While most STIs are not transmitted through shared clothing, certain infections can indeed spread this way. The risk depends on the specific type of infection and how long the pathogen can survive outside the human body.
STIs Not Transmitted Through Underwear
Many common sexually transmitted infections do not spread through clothing because their pathogens cannot survive long outside the warm, moist environment of the human body. For instance, human immunodeficiency virus (HIV) is transmitted through specific bodily fluids like blood, semen, pre-ejaculatory fluid, rectal fluids, vaginal fluids, and breast milk, and it quickly becomes inactive once exposed to air. Similarly, herpes simplex virus (HSV), which causes genital herpes, requires direct skin-to-skin or mucous membrane contact for transmission and does not survive well on inanimate objects like underwear.
Syphilis bacteria, Treponema pallidum, are also extremely fragile and die quickly outside the body, making transmission via shared clothing highly unlikely. Human papillomavirus (HPV), responsible for genital warts and certain cancers, is primarily spread through direct skin-to-skin contact, typically during sexual activity. These pathogens generally require intimate contact with mucous membranes or broken skin for successful transmission.
Infections That Can Spread Through Clothing
Some infections, though often associated with sexual contact, can indeed be transmitted through shared clothing or bedding. Pubic lice, commonly known as “crabs,” are tiny parasites that infest coarse body hair, including the pubic area. They can detach from a host and survive for up to 24-48 hours on items like underwear, towels, or bedding, allowing for non-sexual transmission. Symptoms include intense itching in the affected areas, often worsening at night, and visible nits (lice eggs) or adult lice.
Scabies is another parasitic infestation caused by microscopic mites that burrow into the top layer of the skin. These mites can survive for 24-36 hours off the human body, making transmission possible through direct, prolonged skin contact or sharing infested clothing, towels, or bedding. A characteristic symptom is a severely itchy rash, often appearing as tiny red bumps or burrows, which typically intensifies after showering or at night.
Molluscum contagiosum is a viral skin infection that causes small, firm, pearly or flesh-colored bumps with a dimple in the center. This virus can be transmitted through direct skin-to-skin contact or through contact with contaminated objects, such as shared clothing or towels.
Low Risk, Possible Transmission
While the risk is very low, some bacterial and parasitic infections could be transmitted via contaminated underwear under specific conditions. Chlamydia and gonorrhea are bacterial infections that primarily infect mucous membranes. The bacteria causing these infections (Chlamydia trachomatis and Neisseria gonorrhoeae) are delicate and do not survive well outside the body for extended periods.
However, if underwear is heavily soiled with discharge from an infected individual and immediately worn by another person while still moist, an extremely rare transmission could occur. Trichomoniasis, caused by the parasite Trichomonas vaginalis, can survive for a few hours on damp surfaces like towels or wet clothing, allowing for low-risk transmission if shared immediately.
Hepatitis B virus is primarily transmitted through blood and other body fluids. While it can survive on surfaces for up to a week, transmission from underwear is considered exceptionally rare due to the need for direct entry into the bloodstream.