Once treatment has been started, patients with early syphilis should have repeated testing every three months for one full year. Within a few hours after the spirochetes penetrate the skin or a mucous membrane, they enter the bloodstream, and usually in about a week they spread throughout the body. Usually firm or hard, the chancre may resemble a blister, pimple, or ulcerated open sore. In men, it appears usually on or near the head of the penis. In women, the chancre is commonly found on the labia, but it may be concealed inside the vagina, where it may not be felt or seen.
Chancres sometimes develop elsewhere, such as on the lips of the mouth, a breast, or a finger.
They also may appear in the anal region. The nearby lymph nodes become hard and swollen. Even if no treatment is given, the chancre will disappear in 10 to 40 days, often leading to the false conclusion that the disease is cured. Occasionally a chancre fails to develop or is too small to be noticed. Primary syphilis can be cured with penicillin in adequate doses and with other antibiotics, such as tetracycline.