Syphilis: Stages, Symptoms, and Treatment in Singapore

Syphilis is a sexually transmitted infection caused by the bacterium Treponema pallidum. It progresses through distinct stages if untreated and can affect multiple organ systems over time. Syphilis is curable with appropriate antibiotic treatment when diagnosed early. Many people in the early or latent stages have no symptoms, which is why STI screening is important for sexually active adults, especially if there has been potential exposure.

Symptoms vary by stage. The first sign is often a single painless ulcer (chancre) at the site of infection (genitals, anus, or mouth), which heals on its own within weeks. Later, a non-itchy rash may appear on the body, often on the palms and soles, sometimes with fever, sore throat, swollen glands, hair loss, or fatigue. Some people have no symptoms at all even with active infection.

The first sign of syphilis (a chancre) typically appears between 10 and 90 days after exposure, often around 3 weeks. The chancre is often painless and may be missed, especially if it is internal (inside the vagina, anus, or mouth). Some people develop the secondary stage rash weeks to months later, and others remain asymptomatic for years. Because of this variable timing, blood testing is recommended after potential exposure even if you feel well.

Syphilis progresses through four stages if untreated. Primary syphilis: a single painless ulcer (chancre) that heals on its own. Secondary syphilis: rash, mucous patches, swollen glands, fever, hair loss. Latent syphilis: no symptoms despite ongoing infection (can last years). Tertiary syphilis: serious complications affecting heart, brain, nerves, eyes, and bones, occurring years to decades later. Diagnosis and treatment at any stage prevents further progression.

Syphilis is transmitted through direct contact with an infectious lesion (chancre or rash), most commonly during vaginal, anal, or oral sex with an infected person. It can also pass from mother to baby during pregnancy or childbirth (congenital syphilis). Syphilis is not spread through casual contact such as hugging, sharing utensils, or using the same toilet.

Yes. Syphilis is curable with appropriate antibiotic treatment prescribed by a doctor, especially when diagnosed in the primary or secondary stages. Treatment in later stages can stop further damage but may not reverse damage already done to organs. Having had syphilis does not produce lasting immunity, so reinfection is possible if you are re-exposed. Sexual partners should also be tested and treated to prevent reinfection.

Syphilis is treated with prescription antibiotics, typically penicillin given as an intramuscular injection. Your doctor will choose the appropriate antibiotic, dosing, and number of doses based on the stage of syphilis, your situation, allergies, and current clinical guidance. Avoid sexual activity until treatment is completed as advised and recent partners have been treated. Follow-up blood tests are usually recommended to confirm treatment success.

Untreated syphilis may cause serious long-term complications, particularly in the tertiary stage. These may include damage to the cardiovascular system (aortic aneurysm, heart valve disease), nervous system (neurosyphilis affecting brain, spinal cord, or nerves), eyes (ocular syphilis), bones, and other organs. Untreated syphilis in pregnancy may cause stillbirth, neonatal death, or congenital syphilis. Untreated infection also increases the risk of contracting HIV.

Syphilis risk can be reduced by using condoms consistently during vaginal, anal, or oral sex, having regular STI screenings (especially with new or multiple partners), maintaining a mutually monogamous relationship with a tested uninfected partner, and avoiding contact with visible lesions or rashes. Open conversations with partners about STI status also support prevention. Pregnant women should be screened to prevent congenital syphilis.

You can get tested at Mediway through our STD testing service. Syphilis is typically diagnosed via a blood test, with optional swab from a chancre if a sore is present. The doctor will recommend the appropriate tests based on your symptoms and possible exposure. Learn more on our STD testing in Singapore page, or speak to our team to arrange a confidential consultation.