Syphilis: Symptoms, Causes, and Effective Treatment in the UK

Syphilis is a systemic bacterial infection caused by the bacterium Treponema pallidum. While it was once much rarer, UK health data has shown a significant rise in cases over the last decade. It is primarily a sexually transmitted infection (STI), passed through direct contact with a syphilis sore (known as a chancre) during vaginal, anal, or oral sex. It can also be passed from a mother to her unborn baby during pregnancy (congenital syphilis).

Unlike some other STIs that remain localised, the bacteria that cause syphilis can travel through the bloodstream, affecting various organs over time. This makes early diagnosis and treatment critical to preventing long-term complications. In the UK, sexual health clinics (GUM clinics) provide free, confidential testing and treatment for syphilis.

Syphilis is often referred to as 'the great imitator' because its symptoms can look like many other conditions. The infection typically progresses through three main stages if not treated.

Primary Syphilis

The first sign is usually a small, painless sore called a chancre. It appears at the spot where the bacteria entered the body—often the genitals, anus, or mouth. Because it is painless and can be hidden inside the vagina or rectum, many people do not notice it. The sore usually heals on its own within three to six weeks, but this does not mean the infection is gone; it simply means the disease has moved to the next stage.

Secondary Syphilis

A few weeks after the sore heals, you may experience a skin rash that doesn't itch. This rash often appears on the palms of the hands and soles of the feet but can cover the whole body. Other symptoms at this stage include:

• Swollen lymph nodes
• Fever and muscle aches
• Sore throat and patchy hair loss
• White patches in the mouth
• Tiredness (fatigue)

Latent and Tertiary Syphilis

If untreated, the infection enters a 'latent' stage where there are no visible symptoms. This can last for years. In some cases, the infection progresses to tertiary syphilis years or even decades later. This is the most serious stage and can result in damage to the heart, brain, eyes, and bones.

In the UK, the standard way to test for syphilis is a simple blood test. The test looks for antibodies that your body produces to fight the infection. If you have an active sore, a clinician may also take a swab of the fluid from the sore to look for bacteria under a microscope.

Treatment is straightforward and highly effective when started early. According to NICE and NHS guidelines:

• Antibiotics: The primary treatment is an injection of penicillin into the buttock. For early-stage syphilis, one dose is often enough. If the infection has been present for longer, you may need weekly doses for three weeks.
• Alternatives: If you have a penicillin allergy, a clinician may prescribe a course of antibiotic tablets such as doxycycline for 14 to 28 days.

It is essential to finish the full course of treatment and avoid any sexual contact (including oral sex) until your clinician confirms you are no longer infectious. It is also vital to inform previous sexual partners so they can be tested.

Because syphilis is spread through direct contact with sores, the most effective way to reduce risk is to practice safer sex. Using a condom every time you have vaginal, anal, or oral sex significantly lowers the risk, though it is not 100% effective if the sore is located on an area not covered by the condom.

Regular STI screenings are recommended for anyone with new or multiple sexual partners. In the UK, gay, bisexual, and other men who have sex with men (MSM) are advised to have more regular check-ups, as this group is statistically at a higher risk for syphilis outbreaks. Additionally, all pregnant women in the UK are offered a syphilis blood test during their routine antenatal screening to protect the health of the baby.

If you are concerned about your sexual health or have noticed unusual symptoms, speaking with a GP can be a helpful first step. While online GPs cannot perform physical blood tests themselves, they can provide a confidential consultation to discuss your symptoms, assess your risk, and advise on the next steps.

You should seek a consultation if:

• You have noticed a new, painless sore on your genitals or mouth.
• You have a mysterious rash on your palms or soles.
• You have been informed by a partner that they have tested positive for an STI.
• You want advice on where to find the nearest specialist sexual health service for discreet testing.

A GP can also provide referral advice or private prescriptions for certain conditions, ensuring you navigate the UK healthcare system efficiently.