Syphilis causing hair loss is a lesser-known but clinically important presentation of this increasingly common sexually transmitted infection. Known as syphilitic alopecia, hair loss associated with syphilis typically emerges during the secondary stage of infection, when the bacterium Treponema pallidum spreads through the bloodstream. With syphilis diagnoses in England reaching their highest level since the 1940s, awareness of atypical symptoms — including patchy hair loss — is more important than ever. This article explains how and why syphilis can cause hair loss, how it is diagnosed and treated on the NHS, and when to seek medical advice.

Can Syphilis Cause Hair Loss?

Yes, syphilis can cause hair loss — called syphilitic alopecia — during the secondary stage, when Treponema pallidum spreads systemically and disrupts the normal hair growth cycle.

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Yes, syphilis can cause hair loss, though it is not among the most widely recognised symptoms of the infection. Hair loss associated with syphilis — known medically as syphilitic alopecia — typically occurs during the secondary stage of the disease, which usually develops between six weeks and six months after the initial infection. At this stage, the bacterium Treponema pallidum has spread systemically through the bloodstream, affecting multiple organ systems, including the skin and hair follicles.

The exact mechanism by which syphilis causes hair loss is not fully understood and remains a subject of ongoing investigation. It is hypothesised to involve a combination of immune-mediated inflammatory disruption of the normal hair growth cycle — pushing follicles prematurely into the telogen (resting) phase — and, in some cases, direct involvement of the follicle by the organism, as suggested by histological and PCR findings in certain studies. Neither mechanism has been definitively established.

Syphilitic alopecia is relatively uncommon even among those with secondary syphilis; reported estimates vary, and precise UK prevalence data are limited. In rare cases, hair loss may be the sole presenting feature of secondary syphilis — a presentation sometimes referred to as essential syphilitic alopecia — which can make diagnosis particularly challenging.

Awareness of the full range of syphilis symptoms, including hair loss, is increasingly important. The UK Health Security Agency (UKHSA) annual STI surveillance reports have documented a sustained and significant rise in syphilis diagnoses in England over recent years, with over 8,000 diagnoses recorded in 2022 — the highest number since the 1940s. Both patients and clinicians should be alert to less typical presentations of the infection.

Recognising Syphilitic Alopecia: Signs and Symptoms

Syphilitic alopecia most characteristically presents as irregular, 'moth-eaten' patchy hair loss on the scalp, though diffuse shedding and alopecia areata-like patterns also occur; it is usually non-scarring and non-itchy.

Syphilitic alopecia can present in more than one pattern, and recognising its range of appearances is important for timely diagnosis.

The most characteristic pattern is described as 'moth-eaten' alopecia — irregular, patchy areas of hair thinning or loss, most commonly affecting the scalp, but potentially also involving the eyebrows, eyelashes, and beard area. These patches are typically small, multiple, and scattered, giving the scalp an uneven appearance. However, syphilitic alopecia can also present as a diffuse telogen effluvium (generalised shedding) or, less commonly, in a pattern resembling alopecia areata. Clinicians should be aware of this range when considering the differential diagnosis.

Unlike some other forms of alopecia, syphilitic hair loss is generally non-scarring, meaning the hair follicles themselves are not permanently destroyed. The affected areas are usually not inflamed, and pruritus (itching) is typically absent or minimal, though it can occasionally occur. These features can make the hair loss easy to overlook or attribute to other causes such as stress, nutritional deficiency, tinea capitis, or alopecia areata.

Syphilitic alopecia rarely occurs in isolation, though it can do so (see essential syphilitic alopecia, above). It is most often accompanied by other features of secondary syphilis, which may include:

• A widespread skin rash, often affecting the palms of the hands and soles of the feet

• Flu-like symptoms such as fatigue, fever, and swollen lymph nodes

• Mucous membrane lesions (known as mucous patches) in the mouth or genitals

• Condylomata lata — flat, wart-like lesions in moist skin areas

Recognising these associated features is important, as the combination of symptoms can prompt earlier testing and diagnosis. If hair loss appears alongside any of the above, a sexual health assessment should be sought promptly.

Diagnosis and Testing Through the NHS

Syphilis is diagnosed via blood tests combining treponemal antibody tests (which remain positive for life) and non-treponemal tests such as RPR or VDRL to assess disease activity; free testing is available at NHS sexual health clinics.

Diagnosing syphilitic alopecia requires confirming an underlying syphilis infection, as the hair loss itself does not have an appearance exclusive to syphilis. A dermatologist or sexual health clinician will typically take a full clinical history, including sexual health history, and perform a physical examination before requesting appropriate investigations.

Blood tests are the primary method for diagnosing syphilis in the UK. Testing follows a combination approach in line with BASHH (British Association for Sexual Health and HIV) guidelines and UK Standards for Microbiology Investigations (UK SMI), including:

• Treponemal antibody tests (e.g., enzyme immunoassay or TPPA), which detect antibodies to T. pallidum. It is important to note that treponemal tests generally remain positive for life following infection, even after successful treatment, and therefore cannot alone distinguish active from past infection.

• Non-treponemal tests such as the RPR (Rapid Plasma Reagin) or VDRL (Venereal Disease Research Laboratory) test, which reflect disease activity and are used to monitor treatment response through serial titre measurements.

Where active mucocutaneous lesions are present, dark-field microscopy or PCR testing of lesion material may also be used to aid diagnosis.

A skin biopsy of an affected scalp area is seldom required and may yield non-specific findings; it is generally reserved for diagnostically uncertain cases. When performed, histological features may include perivascular lymphoplasmacytic infiltrates and plasma cells around hair follicles.

In line with BASHH guidance, all individuals being assessed for syphilis should be offered comprehensive STI screening, including testing for HIV and hepatitis B/C, as co-infections are common.

NHS sexual health clinics (also known as GUM — genitourinary medicine — clinics) offer free, confidential testing for syphilis and other STIs. Testing can also be accessed via a GP, or through home testing kits available through some NHS services and approved providers. BASHH clinical guidelines and UKHSA standards provide the primary framework for STI testing and management across the UK.

Treatment Options and Hair Regrowth After Syphilis

Benzathine benzylpenicillin by single intramuscular injection is the first-line treatment for secondary syphilis; most patients see significant or complete hair regrowth within three to six months of successful treatment.

The treatment of syphilitic alopecia is centred on treating the syphilis infection itself, rather than addressing the hair loss directly. Once the infection is effectively managed, hair regrowth typically follows without the need for additional hair-specific interventions.

Benzathine benzylpenicillin (2.4 million units given as a single intramuscular injection) remains the first-line treatment for early syphilis, including secondary syphilis, in line with BASHH guidelines. For individuals with a confirmed penicillin allergy, doxycycline 100 mg twice daily orally for 14 days is the recommended alternative. Doxycycline is contraindicated in pregnancy and in children; pregnant individuals with a penicillin allergy should be referred urgently to a specialist centre for penicillin desensitisation, as penicillin remains the only reliably effective treatment in pregnancy. Suspected or confirmed syphilis in pregnancy should prompt immediate involvement of the antenatal team and a sexual health specialist.

Patients should be counselled about the Jarisch–Herxheimer reaction — a self-limiting systemic reaction (fever, rigors, myalgia, and transient worsening of rash or symptoms) that can occur within the first 24 hours of starting antibiotic treatment. It is caused by the release of bacterial products as T. pallidum is killed. Management is supportive (rest, adequate hydration, paracetamol); patients should be advised to seek medical attention if symptoms are severe or prolonged.

If ocular symptoms (visual disturbance, uveitis), hearing loss, or neurological symptoms (severe headache, focal neurology, confusion) are present at any stage, urgent specialist referral is required, as ocular, otological, or neurosyphilis may necessitate different treatment regimens (typically intravenous benzylpenicillin) and specialist management.

Following successful treatment, most patients with syphilitic alopecia experience significant or complete hair regrowth within three to six months. Because the alopecia is non-scarring in the majority of cases, the hair follicles retain their capacity to regenerate once the inflammatory and infectious process has resolved.

Serological follow-up using RPR or VDRL titres is essential to confirm treatment response. A fourfold decline in titre within six to twelve months is generally considered indicative of treatment success. For early syphilis, BASHH recommends follow-up at approximately 3, 6, and 12 months after treatment. If titres fail to decline as expected, or rise, re-treatment and further investigation are required.

Patients are also advised to:

• Avoid sexual contact until they and their partner(s) have completed treatment and any lesions have fully resolved, or as specifically advised by their sexual health clinic — note that serological tests may remain positive long-term and are not a guide to when sexual activity can resume

• Inform recent sexual partners so they can be tested and treated if necessary; sexual health clinics can assist with partner notification

• Attend all follow-up appointments as recommended by their clinician

• Report any suspected adverse reactions to treatment via the MHRA Yellow Card scheme (yellowcard.mhra.gov.uk)

There is no evidence that additional hair loss treatments (such as minoxidil or corticosteroids) are required for syphilitic alopecia specifically, though a dermatologist may assess this on an individual basis if regrowth is delayed.

When to Seek Medical Advice

Anyone with unexplained patchy hair loss — especially alongside a rash, mouth ulcers, or flu-like symptoms — should contact their GP or an NHS sexual health clinic promptly; same-day urgent attention is needed if visual, hearing, or neurological symptoms develop.

Anyone who notices unexplained, patchy hair loss — particularly if it follows a 'moth-eaten' pattern or is accompanied by other symptoms such as a skin rash, mouth ulcers, genital sores, or flu-like illness — should seek medical advice promptly. While there are many potential causes of hair loss, the possibility of an underlying STI such as syphilis should not be overlooked, especially given the rising rates of infection in the UK.

You should contact your GP or visit an NHS sexual health clinic if you:

• Have noticed patchy or unusual hair loss without a clear explanation

• Have had unprotected sexual contact and are experiencing any symptoms of secondary syphilis

• Have been informed by a sexual partner that they have been diagnosed with syphilis

• Are pregnant and concerned about possible syphilis exposure — syphilis can be passed to an unborn baby (congenital syphilis), with potentially serious consequences; contact your midwife or antenatal team urgently, as routine NHS antenatal screening for syphilis is offered to all pregnant women

Seek same-day urgent medical attention if you develop any of the following alongside symptoms of syphilis, as these may indicate involvement of the eyes, ears, or nervous system:

• Sudden changes in vision, eye pain, or redness (possible ocular syphilis)

• New or unexplained hearing loss or tinnitus (possible otosyphilis)

• Severe headache, neck stiffness, confusion, or focal neurological symptoms (possible neurosyphilis)

Sexual health clinics offer same-day or walk-in appointments in many areas, and consultations are entirely confidential. You can find your nearest clinic through the NHS website (nhs.uk). Home testing kits for syphilis are also available; however, a positive result must always be followed up with an in-person clinical assessment for confirmatory testing and appropriate management.

Early diagnosis and treatment are key to preventing complications, protecting partners, and ensuring the best chance of full recovery — including complete hair regrowth. Syphilis is a treatable infection, and outcomes are excellent when it is identified and managed early. If you are unsure whether your symptoms are related to syphilis or another condition, a healthcare professional can help guide appropriate testing and next steps.

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