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

Secondary syphilis causes distinctive patchy, moth-eaten hair loss as part of its systemic dissemination phase — it is non-scarring and fully reversible with penicillin treatment, often appearing in people who never noticed the primary sore. HIV-related hair loss occurs through immune suppression, medication effects, and nutritional deficiencies. No other common STDs directly cause hair loss. Testing available in Houston, Los Angeles, New York City, Atlanta, and Chicago.

Hair loss is not a typical STD symptom — but syphilis is the clear exception, and understanding its specific pattern helps both patients and clinicians recognize when a dermatological complaint might have an infectious cause.

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 thinning scattered across the scalp, giving the characteristic moth-eaten appearance. Involvement can extend to the eyebrows, eyelashes, beard, and pubic hair.

The mechanism: Treponema 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. I have had patients come in asking about hair loss, and the full picture — patchy scalp involvement, subtle palmar rash, lymphadenopathy — made secondary syphilis an obvious clinical diagnosis confirmed by bloodwork the same day.

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 pushes a large proportion of hair follicles simultaneously into the resting 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 can also cause diffuse hair thinning.

Some antiretroviral medications are associated with hair changes. Efavirenz has been reported to cause hair texture changes and mild thinning in some patients. Newer antiretroviral regimens have fewer dermatological side effects than older ones. Seborrheic dermatitis, significantly more common in people with HIV, can also cause scalp inflammation and associated hair loss.

When Hair Loss Should Prompt Syphilis Testing

The clinical scenarios where hair loss should prompt syphilis serology include 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 anywhere on the body, even if subtle; and 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, testing is worthwhile whenever it is on the differential.

When to Seek Evaluation

• Patchy scalp hair loss with an irregular moth-eaten pattern: possible secondary syphilis — get a syphilis blood test within 1–2 days.

• Hair loss accompanied by a rash anywhere on the body, particularly the palms or soles: highly characteristic of secondary syphilis — same-day evaluation.

• HIV-positive and experiencing new or worsening hair loss: medication review and nutritional assessment warranted — discuss with your HIV care provider.

• Hair loss beginning 2 to 4 months after a significant illness or STD diagnosis: possible telogen effluvium — resolves spontaneously but underlying cause should be confirmed.

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.

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.

What does syphilis hair loss look like compared to normal hair loss?

Syphilitic alopecia has a distinctive moth-eaten appearance — multiple small, irregular patches of thinning randomly distributed across the scalp, eyebrows, and beard. It does not follow the hairline recession pattern of male pattern baldness, nor the single circular patches of alopecia areata. The randomness and the presence of other secondary syphilis symptoms are the key distinguishing features.

Related reading: Syphilis Symptoms: All Four Stages · STDs and Neurological Symptoms · Can You Have an STD With No Symptoms?