Syphilis is a sexually transmitted infection caused by the bacterium Treponema pallidum. It progresses through several stages, each with different signs and symptoms. One of the hallmark symptoms of syphilis is a rash, which can appear at different parts of the body depending on the stage of infection.
Primary syphilis rash
In the early stages of syphilis infection, a rash may appear at the site where the bacteria first entered the body. This is called a “primary syphilis rash.”
The primary syphilis rash typically shows up:
- On the genitals, around the penis or vagina
- On the mouth or lips
- Around or inside the anus
- On the fingers
Less commonly, it may appear on other parts of the body where contact occurred such as the neck, breasts, or thighs.
The primary syphilis rash appears around 3 weeks after infection but can range from 10 to 90 days. It begins as one or more small, painless sores called chancres. The sores are firm, round, and painless. Without treatment, they last 3 to 6 weeks and will heal on their own.
Secondary syphilis rash
If syphilis is not treated during the primary stage, it can progress to the secondary stage. The secondary stage is characterized by a diffuse rash that can appear anywhere on the body.
Common locations for the secondary syphilis rash include:
- On the palms of the hands and soles of the feet
- On the neck, face, arms, legs, chest, back, and abdomen
- Around the genitals and anus
The secondary syphilis rash appears around 2 to 8 weeks after the primary chancre heals. It often begins as reddish-brown spots or patches that are flat or slightly raised. The rash is not itchy and is often described as having a symmetrical, “measles-like” appearance.
As the rash evolves, it changes appearance and may take on different characteristics:
- Macular – Red or reddish-brown flat spots
- Papular – Small, solid, raised bumps
- Pustular – Bumps containing pus
- Plaque – Large, flat, raised lesions
The rash can be widespread and cover large portions of the body, or it may be concentrated in just a few areas. Without treatment, the secondary syphilis rash usually lasts up to 6 weeks before clearing.
Latent syphilis
After the secondary stage, syphilis enters a latent phase. During latent syphilis, there are no signs or symptoms. Latent syphilis is divided into early latent (1 year after infection). The latent phase can persist for years before the infection progresses.
During the latent stage, no rashes are present. However, syphilis is still active in the body and transmissible during this phase.
Tertiary syphilis
The final stage of syphilis is called tertiary or late syphilis. It develops around 3 to 15 years after infection, and about one-third of people who don’t receive treatment will progress to this advanced stage.
During tertiary syphilis, the bacteria spreads to affect different organ systems, causing widespread damage throughout the body.
Symptoms of tertiary syphilis include:
- Gummas – Tumor-like growths that form on organs
- Cardiovascular problems like aortic aneurysms
- Neurosyphilis – Infection of the brain and nervous system
Skin findings during tertiary syphilis can include rashes and growths:
- Gummatous rashes – Firm, painless, nodular lesions on the skin
- Rhagades – Long, painful fissures around the mouth, nose, or genitals
- Condylomata lata – Moist, wart-like growths in warm, moist areas like the genitals and mouth
Congenital syphilis rash
Syphilis can also spread from a pregnant woman to her unborn baby, resulting in congenital syphilis. Congenital syphilis occurs when the infection spreads through the placenta to a developing baby.
Babies born with congenital syphilis may develop skin rashes that include:
- Bullous lesions – Fluid-filled blisters
- Desquamation – Shedding of skin layers in large sheets
- Mucous patches – Flat, moist, grayish-white lesions in the mouth
- Papules – Firm bumps around the nose, mouth, and diaper area
These rashes are often widespread and visible on any part of the body.
When to see a doctor
It’s important to recognize the signs and symptoms of a syphilis rash so you can seek medical treatment right away. While the rash will eventually clear up on its own without treatment, the underlying syphilis infection can still damage your health.
See a healthcare provider if you develop any unusual rash, especially if it is accompanied by symptoms like:
- Sores or bumps on the genitals, around the anus, or in the mouth
- Muscle aches
- Fever
- Swollen lymph nodes
- Fatigue
- Hair loss
- Headaches
Also get tested for syphilis if you have engaged in unprotected sex and are at risk of sexually transmitted infections. Syphilis screening is recommended at least yearly for sexually active people who have multiple or anonymous partners.
Diagnosis
To diagnose syphilis, your doctor will perform a physical exam to look for signs of a rash. They may also take samples or scrapes from active sores to examine under a microscope.
Blood tests can confirm syphilis infection by looking for antibodies produced in response to the bacteria. These include:
- Nontreponemal antibody tests (VDRL, RPR)
- Treponemal antibody tests (TP-PA, FTA-ABS)
Your doctor may also order tests to check for damage to different organs including a neurological exam, eye exam, and echocardiogram of your heart.
Treatment
Syphilis is treated with antibiotics, usually penicillin. The type of medication and length of treatment depends on the stage of syphilis:
- Primary, secondary, or early latent syphilis – Benzathine penicillin G given as 2-3 intramuscular injections over a period of 1-2 weeks.
- Late or unknown latent syphilis – Benzathine penicillin G given as 3 intramuscular injections over a period of 3 weeks.
- Tertiary syphilis – A longer course of penicillin treatment, or penicillin administered intravenously for neurosyphilis.
Treatment in the early stages can prevent progression to later stages and permanent symptoms. However, damage that has already occurred cannot be reversed.
All sexual partners from the past 3 months, or from the onset of symptoms if within the past year, should be tested and treated.
Babies born with congenital syphilis are treated with an injection of penicillin every day for the first 7-10 days, then weekly injections until the blood work returns to normal.
Conclusion
Syphilis goes through different stages, each of which can produce characteristic rashes. The primary and secondary rashes can occur anywhere on the body but are most common around the genitals and mouth. Later rashes tend to occur as growths or lesions affecting the skin and mucous membranes. Recognizing the signs of syphilis rashes allows for prompt diagnosis and treatment to prevent serious complications.