Hair loss is one possible symptom of the sexually transmitted infection syphilis. It’s thought to occur due to an immune response to the bacteria causing the infection.

Syphilis is a sexually transmitted infection caused by the bacteria Treponema pallidum. It affects people of all genders and is transmitted through direct contact with syphilitic chancres, or sores. The sores typically develop on or in the:

  • mouth
  • anus
  • penis
  • vagina

Babies can also contract syphilis if their mother has an untreated infection.

Besides chancres, which are often painless, other symptoms may include:

  • a rash on the palms, soles, or elsewhere on the body that does not itch
  • headaches
  • swollen lymph nodes
  • fatigue
  • fever
  • weight loss
  • aching joints

Hair loss is another common symptom.

Syphilis is easily treatable but can cause serious complications to various body systems when it’s left untreated.

This article covers why and how syphilis causes hair loss, symptoms, and how it’s treated.

Syphilis is broken down into four stages:

  1. Primary syphilis occurs about 3 weeks after a person contracts the bacteria and begins with a sore that remains for 2 to 6 weeks.
  2. Secondary syphilis occurs following primary syphilis and can begin as late as 6 months following exposure to the bacteria. This is where most other symptoms appear.
  3. In latent syphilis, the symptoms disappear, but the bacteria remain in the body. This stage begins about 1 to 2 years following exposure.
  4. Tertiary syphilis can occur many years following initial exposure. It can cause many serious complications, such as:
    • vision loss
    • hearing loss
    • memory loss
    • tissue and bone damage
    • heart disease
    • infection of the brain or spinal cord
    • neurological disorders like stroke and meningitis

Hair loss is a possible symptom during secondary syphilis. The condition is known as alopecia syphilitica and affects about 3% to 7% of people with the infection.

While more research is needed about the exact relationship between syphilis and hair loss, it’s believed that the hair loss occurs as an inflammatory immune response to the bacteria, which can disrupt the hair growth cycle. Another theory posits that the hair loss occurs when a buildup of lymphocytes, a type of white blood cell, due to an immune response plugs hair follicles.

Secondary syphilis treatment and hair loss

The main treatment for secondary syphilis is one of three antibiotics. One uncommon but serious side effect from use of antibiotics for the treatment of syphilis is Jarisch-Herxheimer reaction (JHR). This effect may cause several symptoms within the first 24 hours after treatment:

  • fever and chills
  • muscle, ligament, and tendon pain
  • joint pain and stiffness
  • headaches
  • transient hair loss

In pregnant people, JHR may cause preterm labor or cause fetal distress.

Syphilis hair loss presents as the loss of hair on your scalp or elsewhere on your body in a:

  • diffuse pattern of evenly thinned hair on the scalp
  • “moth-eaten” pattern of small, irregularly bordered patches of hair loss
  • combination of diffuse and moth-eaten

It may sometimes be confused for other types of hair loss, such as that of alopecia areata, telogen effluvium, or tinea capitis.

The hair loss may be accompanied by the characteristic painless rash.

A doctor will likely ask you about your medical and sexual history, perform a visual exam, as well as order antibody serology, immunohistochemistry (IHC), or polymerase chain reaction (PCR) tests to make a diagnosis.

It’s important to see a medical professional promptly if you experience any symptoms that may be related to syphilis, such as:

  • sores following sexual activity
  • a rash that does not itch
  • headaches
  • swollen lymph nodes
  • fatigue
  • fever
  • weight loss
  • aching joints
  • hair loss

Medical professionals treat syphilis with antibiotics.

The first-line treatment of syphilis hair loss typically includes an injection of the antibiotic benzathine penicillin G, which leads to hair regrowth weeks to months after administration.

For people with a known penicillin allergy, a doctor may prescribe oral doxycycline (Vibramycin-D, Efracea, Periostat) or tetracycline (Sumycin, Actisite, and Achromycin V).

Hair regrowth is expected between 5 weeks and 3 months after receiving treatment.

Following treatment, your doctor will test your blood to confirm the infection is gone.

Is syphilis hair loss permanent?

Syphilis hair loss is temporary if the underlying infection is treated promptly.

How long does syphilis hair loss last?

Hair loss will last either until about 5 weeks to 3 months after treating your syphilis or until the syphilis progresses from the secondary to the latent stage. The latent stage begins about 1 to 2 years after initial exposure to the infection.

Which other STDs cause hair loss?

Syphilis is the only sexually transmitted infection known to directly cause hair loss. However, certain treatments for other STIs, such as HIV, gonorrhea, chlamydia, and herpes, may cause temporary hair loss.

Hair loss is one less common symptom of syphilis, a sexually transmitted disease. It occurs during the STI’s second stage. If you think you have syphilis, it’s important to see a medical professional promptly. The infection is easily treatable. But if left untreated, it can cause serious permanent damage to your body.