Syphilis is a systemic bacterial infection usually caused by sexual contact with an infected person. It is known as the "great imitator and mimicker" because of its diverse clinical presentations. There are four stages of infection and many organ systems can be affected at a time.

Last Updated: February 24, 2024

The bacteria Treponema pallidum causes syphilis. An infected person spreads the bacteria through vaginal, anal, or oral sex. The bacteria can enter the body through the anus, vagina, penis, mouth, cut, or wound. 

If a pregnant woman has syphilis, she can pass it on to her baby. However, syphilis cannot be transmitted by touching things like toilet seats, utensils, or doorknobs.


Syphilis is common in the developing world, especially among the poor who don't have easy access to medical care. Since this disease is transmitted through sexual contact, people who have multiple partners are more likely to get syphilis.

Promiscuity is a big part of how syphilis spreads and in 2019, 10.8% of people who worked in the sex industry worldwide had active syphilis. Having syphilis is linked to an increased risk in getting infected with HIV

The most common sign of syphilis is a single, non-tender genital sore. Patients can also have more than one sore, not on their genitalia, such as the fingers, nipples, tonsils, or oral mucosa. They are often accompanied by lymphadenopathy (lymph node swelling), which can be painful or not. If these skin lesions are not treated they can worsen, spreading through the blood, and this stage is called secondary syphilis.


Secondary syphilis can present differently depending on where the infection has spread to. Examples of other symptoms include condyloma lata (papulosquamous eruption), lesions on the hands and feet, macular rash, diffuse lymphadenopathy, headache, myalgia, arthralgia, pharyngitis, hepatosplenomegaly, hair loss, malaise. Syphilis has been called the "great imitator" because of how varied it can present.


The symptoms of both primary and secondary syphilis can go away on their own, and the patient goes into an early or latent phase in which there are no visible clinical signs. However, the bacteria are still in the patient’s body and some patients in this stage will even move on to the tertiary stage of infection which is marked by the involvement of the heart and the brain.

Aside from history taking and physical examination of the skin and general well-being, doctors usually need at least one positive nontreponemal test (VDRL or RPR) and a positive treponemal test (FTA-ABS, TP-PA) to ascertain that a patient has syphilis. 

Cerebrospinal fluid (CSF) tests are also done on patients with neurological symptoms. When there is a suspicion of cardiovascular involvement, imaging studies such as chest X-rays and CT-scan are also requested.



Treatment depends on the stage of the disease. Treatment for primary, secondary, or early latent syphilis is benzathine penicillin. 

When the brain is involved, neurosyphilis is treated by giving the patient IV penicillin G every day for 14 days. Another option would be to give procaine penicillin once a day and probenecid four times for 10–14 days.

Patients with tertiary or latent syphilis or HIV should get benzathine once a week for three weeks. Alternative treatments include taking doxycycline twice a day for 14 days, ceftriaxone, or tetracycline.

It's crucial to finish therapy after receiving a diagnosis to prevent further illness. To control the spread of infection, it is highly advised to do the following:

  • Use a condom to have safe sex
  • Get checked regularly for syphilis and other STIs
  • Cut down on how many sexual partners you have
  • Don't be shy about asking new partners about their past sexual experiences
  • Tell anyone you've had sexual contact with so that they can also get help



Tudor ME, Al Aboud AM, Leslie SW, et al. Syphilis. [Updated 2022 Nov 28]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan-. Available from:


Cleveland Clinic (2023). Syphilis. Retrieved January 14, 2023, from


Last Updated: February 24, 2024