Can STDs Cause Hair Loss? Syphilis, HIV, and What to Know

Hair loss is not a typical STD symptom — but one specific infection can cause it through a well-documented mechanism, and understanding which one matters for diagnosis and treatment. Secondary syphilis causes patchy "moth-eaten" alopecia as part of its systemic dissemination phase; this hair loss is non-scarring, fully reversible with penicillin treatment, and often the first visible sign that prompts syphilis testing in people who missed or dismissed the primary chancre; HIV-related hair loss occurs through multiple mechanisms including the infection itself, medication effects, and nutritional deficiencies.

Syphilis and Hair Loss: The Mechanism

Secondary syphilis — the stage of Treponema pallidum infection that follows the primary chancre — is characterized by systemic dissemination of the spirochete via the bloodstream. This hematogenous spread carries the bacteria throughout the body, including to the skin and hair follicles. The result is a distinctive hair loss pattern called syphilitic alopecia, which presents as: patchy, irregular areas of hair loss scattered across the scalp; the characteristic "moth-eaten" appearance — multiple small patches of thinning rather than complete bald spots; involvement that can extend to the eyebrows, eyelashes, beard, and pubic hair; simultaneous scalp findings from the secondary syphilis rash (papular lesions that may be subtle at the hairline). The mechanism: T. pallidum causes a perifollicular inflammatory infiltrate that disrupts the normal hair growth cycle, pushing follicles prematurely into the telogen (shedding) phase. This is a non-scarring alopecia — the follicle itself is not destroyed, which is why the hair loss is completely reversible with treatment. After benzathine penicillin G treatment, hair regrowth typically begins within 2 to 3 months and is usually complete within 6 months. Syphilitic alopecia can be the presenting complaint that finally brings a patient to evaluation for what turns out to be secondary syphilis, particularly when the primary chancre was internal (cervical, rectal) or dismissed as a minor skin lesion.

HIV and Hair Loss

HIV can cause hair loss through several distinct mechanisms, each requiring different management. Telogen effluvium from the systemic stress of acute HIV infection or advanced immune suppression: the physiological stress of active infection pushes a large proportion of hair follicles simultaneously into the resting (telogen) phase, causing diffuse shedding approximately 2 to 4 months after the triggering event. Nutritional deficiencies — particularly protein malnutrition, zinc deficiency, and biotin deficiency — associated with advanced HIV disease and weight loss can cause diffuse hair thinning. Antiretroviral medication effects: some ARV drugs are associated with hair changes. Efavirenz (EFV) has been reported to cause hair texture changes and mild thinning in some patients. Indinavir (no longer widely used) caused scalp hair thinning and paradoxical hypertrichosis (increased body hair). Newer ARV regimens have fewer dermatological side effects than older ones. Seborrheic dermatitis (dandruff-like scalp condition) is significantly more common in HIV-positive people than in the general population and can cause diffuse scalp inflammation and some hair loss from the associated inflammation.

Other STD-Related Hair Loss

Beyond syphilis and HIV, other STDs don't directly cause hair loss through specific pathogenic mechanisms. However: systemic illness from any infection can trigger telogen effluvium; immune dysregulation in chronic untreated infection can contribute to diffuse hair shedding; the psychological stress of an STD diagnosis or living with a chronic STD can also trigger telogen effluvium (stress-related hair loss).

When Hair Loss Should Prompt Syphilis Testing

The clinical scenarios where hair loss should prompt syphilis serology: patchy irregular (moth-eaten) alopecia in a sexually active adult, particularly with any recent skin rash or systemic symptoms; hair loss in the eyebrows, eyelashes, or beard in a sexually active adult; scalp hair loss accompanied by a rash on the body, even if subtle; any unexplained hair loss in a patient with risk factors for STD exposure. Syphilis serology (RPR with treponemal confirmatory testing) is a blood test with results in 1 to 2 days. Given that syphilitic alopecia reverses completely with penicillin treatment, testing is worthwhile whenever it's on the differential.

For syphilis RPR and treponemal testing with results in 1 to 2 days, Health Test Express offers panels without a GP referral.

When to Seek Evaluation

Seek evaluation if: you have patchy scalp hair loss with an irregular moth-eaten pattern (possible secondary syphilis); hair loss is accompanied by a rash anywhere on the body, particularly the palms or soles; you are HIV-positive and experiencing new or worsening hair loss (medication review and nutritional assessment); hair loss began 2 to 4 months after a significant illness, major stress, or STD diagnosis (possible telogen effluvium).

Frequently Asked Questions

Can chlamydia or gonorrhea cause hair loss?

No. Chlamydia and gonorrhea are localized bacterial infections that don't cause systemic dissemination leading to hair loss. Hair loss is not a recognized symptom of either infection. If you have hair loss and STD exposure concern, testing for syphilis and HIV — the infections that do cause hair loss — is appropriate.

Will hair grow back after syphilis treatment?

Yes — syphilitic alopecia is fully reversible because the hair follicles themselves are not destroyed. After benzathine penicillin G treatment, hair regrowth typically begins within 2 to 3 months and is usually complete within 6 months. The moth-eaten appearance resolves with the systemic infection.

Can stress from an STD diagnosis cause hair loss?

Yes. Telogen effluvium — diffuse hair shedding triggered by psychological or physiological stress — can follow significant stressors including a new STD diagnosis. This typically appears 2 to 4 months after the triggering event, resolves spontaneously within 6 months, and doesn't cause permanent hair loss.

Related: Syphilis symptoms in women · Syphilis pictures · How does syphilis spread? · Can syphilis be cured? · Get tested today

This article is for informational purposes only and does not constitute medical advice.