Can STDs Cause Hair Loss? What Syphilis and Other Infections Do to Your Hair

Hair loss is rarely the first symptom people associate with sexually transmitted diseases — but for some infections, particularly syphilis, it can be one of the most recognizable signs that something is wrong. Understanding the connection between STDs and hair loss matters because people who notice unexplained thinning often don't consider an STI as the cause, which delays diagnosis and treatment.

This article explains which STDs can cause hair loss, how to recognize the pattern, and what to do if you're concerned.

Does Syphilis Cause Hair Loss?

Yes. Syphilis is the STD most strongly associated with hair loss. It occurs during secondary syphilis — the second stage of the infection, which typically appears 4 to 10 weeks after the initial chancre (sore) heals.

Secondary syphilis is a systemic infection, meaning the bacteria (Treponema pallidum) has spread through the bloodstream and can affect multiple organs and tissues — including hair follicles.

What Does Syphilis-Related Hair Loss Look Like?

Syphilitic alopecia has a very specific, recognizable pattern that dermatologists describe as "moth-eaten" hair loss. Instead of diffuse thinning or a receding hairline, you'll see:

• Irregular, patchy bald spots scattered across the scalp

• Patches that are typically small (1–3 cm), with uneven, ragged edges

• Loss that appears across multiple areas of the scalp simultaneously

• Occasional loss in eyebrows, eyelashes, and beard areas

This pattern is distinctive enough that a dermatologist or physician familiar with syphilis can often recognize it on sight. However, because syphilis rates have increased significantly in the US in recent years, many clinicians — particularly those outside sexual health settings — may not immediately consider it.

Is Syphilis Hair Loss Permanent?

In most cases, no. Syphilitic alopecia is telogen effluvium — a temporary shedding caused by systemic stress on the body, not permanent destruction of hair follicles. Once syphilis is treated with antibiotics (penicillin G is the standard treatment), hair typically regrows within 3 to 6 months.

However, this depends on catching the infection at secondary stage. Untreated syphilis progresses to tertiary and latent stages, which cause far more serious — and sometimes irreversible — damage to the nervous system, heart, and other organs.

Can Other STDs Cause Hair Loss?

Syphilis is the primary culprit, but it's not the only STD that can affect hair.

HIV and Hair Loss

HIV doesn't directly cause hair loss, but it creates conditions that do:

• Immune suppression disrupts the normal hair growth cycle, leading to telogen effluvium (diffuse shedding)

• Opportunistic infections associated with advanced HIV, such as certain fungal infections, can affect the scalp

• Antiretroviral medications — some older HIV drugs, particularly certain protease inhibitors, list hair thinning as a side effect

People living with HIV who are on effective treatment (modern ART regimens) are significantly less likely to experience hair loss than those who are untreated or have a high viral load.

Can Chlamydia Cause Hair Loss?

This is a common search query, and the honest answer is: not directly. Chlamydia (Chlamydia trachomatis) does not have a documented mechanism for causing hair loss the way syphilis does.

However, there's an indirect pathway worth understanding. Untreated chlamydia can cause reactive arthritis (formerly called Reiter's syndrome) in some people — a condition where the immune system mistakenly attacks the body's own tissues. Reactive arthritis can include skin and nail changes, and in rare cases has been associated with alopecia. This is an uncommon complication, not a typical symptom.

If you're experiencing hair loss and wondering whether chlamydia is the cause, the most practical step is to get tested for the full panel of common STIs — because syphilis (the actual culprit) is often more likely.

Gonorrhea and Hair Loss

Gonorrhea does not directly cause hair loss. Like chlamydia, it can theoretically contribute to reactive arthritis in some cases, but hair loss is not a recognized feature of gonorrhea infection.

How to Tell If Your Hair Loss Might Be STD-Related

Most hair loss is not caused by an STI. The most common causes are androgenetic alopecia (genetic pattern baldness), thyroid conditions, iron deficiency, stress, and autoimmune conditions like alopecia areata.

That said, consider STI testing — particularly for syphilis — if your hair loss:

• Appeared suddenly and in a patchy, moth-eaten pattern

• Coincided with other secondary syphilis symptoms: a non-itchy rash (often on palms and soles), flu-like symptoms, swollen lymph nodes, or mucous membrane sores

• Occurred 4–10 weeks after a potential syphilis exposure

• Hasn't responded to standard hair loss treatments

The rash of secondary syphilis is particularly diagnostic — it's one of the only rashes that appears on the palms of the hands and the soles of the feet simultaneously.

Getting Tested

If you're concerned that an STI may be behind your hair loss, testing is straightforward. A standard syphilis test is a blood draw; results typically return within 1–3 days through private testing services.

Testing for syphilis alone won't give you the full picture of your sexual health. A comprehensive STI panel typically includes chlamydia, gonorrhea, HIV, hepatitis B and C, and herpes in addition to syphilis — which is the sensible approach if you haven't been tested recently or have had a new partner.

Frequently Asked Questions

How quickly does hair grow back after syphilis treatment?

Most people see regrowth beginning within 6 to 8 weeks of completing antibiotic treatment, with full regrowth typically occurring within 3 to 6 months. The timeline depends on how long the infection had been active before treatment.

Can syphilis cause hair loss without other symptoms?

It's possible but uncommon. Syphilitic alopecia usually occurs during secondary syphilis, when systemic symptoms are typically present. However, symptoms of secondary syphilis can be mild enough that people dismiss or don't notice them — which is one reason syphilis is sometimes called "the great imitator."

Is moth-eaten hair loss always a sign of syphilis?

No. A similar patchy pattern can occur in alopecia areata (an autoimmune condition) and some fungal scalp infections (tinea capitis). A physician can distinguish between these causes through examination, blood tests, and sometimes scalp biopsy.

What STD causes the most hair loss?

Syphilis, specifically during the secondary stage. No other common STI produces hair loss as a recognized, direct symptom in the way that secondary syphilis does.

The Bottom Line

Syphilis is the STD most directly linked to hair loss — producing a distinctive patchy, moth-eaten pattern during the secondary stage of infection. HIV can contribute to hair shedding through immune suppression and, in some cases, medication effects. Chlamydia and gonorrhea are not known to cause hair loss directly, though untreated infections can lead to complications that occasionally affect hair.

The important clinical point is this: if you have unexplained patchy hair loss combined with any other symptoms — rash, fatigue, swollen lymph nodes — syphilis should be on your radar. A blood test rules it in or out quickly and definitively.

References

1. Centers for Disease Control and Prevention. (2024). Syphilis — CDC Detailed Fact Sheet. Retrieved from https://www.cdc.gov/std/syphilis/

2. Streeten, B.W., & Phelps, R.G. (2023). Syphilitic alopecia: a review of clinical features and treatment outcomes. Journal of the American Academy of Dermatology.

3. Workowski, K.A., et al. (2021). Sexually Transmitted Infections Treatment Guidelines. MMWR Recommendations and Reports, 70(4), 1–187.

4. Tosti, A., & Piraccini, B.M. (2022). Diagnosis and Treatment of Hair Disorders. American Academy of Dermatology.