What causes syphilis?

The bacterium can pass through vaginal, anal, or oral sexual contact when a sore or rash is present. Sores may occur on the genitals, around the anus, in the mouth, or on other skin, and they can be painless or hidden. Transmission can happen even when the person carrying syphilis does not realise they have it. Pregnancy can also allow infection to pass to an unborn baby.

Syphilis develops in stages. An early sore may disappear without treatment, while later symptoms can include a widespread rash, swollen glands, fever, or tiredness. Symptoms fading does not mean the infection has gone.

Arrange an STI test if you have had sexual contact with someone who has syphilis, notice a painless sore or unusual rash, or are pregnant and concerned about exposure. Tell the clinician when the contact occurred and whether you have taken antibiotics, because the timing of tests can affect the plan.

Do not rely on appearance alone. Avoid sexual contact until a clinician has assessed you and explained when it is safe to resume. If testing confirms syphilis, recent partners may need assessment as well. Treatment uses prescribed antibiotics and follow-up testing may be advised.

Seek prompt medical care for a new genital, anal, or mouth sore, a rash involving the palms or soles, or symptoms after a partner has been diagnosed. Contact a clinician urgently if you are pregnant and may have been exposed.

Ask which tests are appropriate now, whether repeat testing is needed, whether partners should be contacted, and what sexual-health precautions apply during treatment.