Syphilis is a sexually transmitted disease (STI) that can cause serious health problems. It can also spread to a baby in the womb.

The first symptom of syphilis is the appearance of a sore, called a chancre. These are firm, round, and painless. They appear where the bacteria enter the body, such as on your mouth, genitals or rectum.

1. Chancres

During the first stage of syphilis, a sore known as a chancre develops at the site where the bacteria enter the body. These ulcers are painless and last about three to six weeks before they heal without treatment.

A chancre is the most common skin rash associated with primary syphilis. Usually it is a reddish, firm, round sore that develops 10 – 90 days (21 days on average) after intimate contact with an infected person.

The rash usually begins on your trunk but quickly spreads to the palms of your hands and soles of your feet. You may also have rashes and wartlike sores in your mouth, vagina, or anus, as well as hair loss, weight loss, or swollen glands.

2. Sores

The earliest sign of syphilis is a painless sore (called a chancre) that develops on your genitals, mouth, or anus. This sore typically goes away in about three to six weeks.

If you have syphilis, your doctor will take a sample of the sore to test for bacteria. They also may do a dark-field microscope exam, which can help diagnose the infection.

The rash and other symptoms can go away after a few weeks, but they can come back over time, especially if you don’t get treatment. You may also have flu-like symptoms and swollen lymph glands, such as in your neck, armpits or groin.

3. Rashes

One of the first signs of syphilis is a skin ulcer (chancre) that develops where the bacteria enter your body. The sore is usually firm, round, and painless.

Chancres can show up anywhere on your body, including your vulva, vagina, anus, penis, scrotum, and lips. You can also get them in your mouth, on the inside of your rectum, under your foreskin, and other areas that are hard to see.

If you don’t get treated, your chancres may grow into a rash, which is the second stage of syphilis. This rash looks rough and reddish-brown and covers your palms of the hands and soles of the feet. It can be mistaken for other skin conditions, but it’s a sure sign of secondary syphilis. It is very contagious and can be passed to anyone you sex with.

4. Fever

The bacteria Treponema pallidum causes syphilis, which is passed from person to person during sexual contact. It can enter your body through the anus, vagina, penis or mouth, and spread throughout your body.

If you are infected with syphilis, you will get a fever. This is caused by the infection and may be accompanied by a headache, sweating, shaking chills or other symptoms.

During primary syphilis, you may develop a chancre (SHANG-kur). This is a firm, round, painless sore that often appears on the spot where the bacteria entered your body.

This sore usually goes away on its own within 3 to 6 weeks. However, you must be treated for the infection to prevent it from moving on to the secondary stage of syphilis. The secondary stage of syphilis can cause problems with the liver, eyes, heart, blood vessels and bones if left untreated.

5. Weight loss

The weight loss that occurs in syphilis infections is usually temporary. But it can cause severe damage to your body, such as organ failure and kidney problems.

If you’re pregnant, syphilis can also make it hard for your baby to grow properly. It can lead to fetal growth restriction (also called small for gestational age or small for date) and low birthweight.

In addition, syphilis can affect the way your placenta works to support your baby in the womb. This can lead to problems with your baby’s health, including stillbirth and neonatal death.