Oral Syphilis: Symptoms, Diagnosis, Treatment and Prevention

Oral Syphilis - STDTestGuru
Oral Syphilis – STDTestGuru

A sexually transmitted infection (STI) caused by the bacteria Treponema pallidum is syphilis. This infection is spread through sexual activity, cuts on the skin, or through mucous membranes. In rare cases, it can spread through direct unprotected close contact with an active lesion or an infected woman who is pregnant can pass on the infection to infants during childbirth or pregnancy. According to WHO, there were 7 million new syphilis infections worldwide in 2020. In 2019, there were 130,000 cases in the US, marking an increase of more than 70% since 2015.

What is oral syphilis?

Syphilis is spread through person-to-person contacts, such as through sexual activity which includes vaginal, anal, or oral sex. During oral sex, syphilis causing bacteria to enter through a cut or opening in the lining of the lips or mouth. This is called oral syphilis. Rarely, the infection can be spread through close, unprotected contact, like kissing. However, the infection cannot spread through sharing eating utensils or drinking glasses. A chancre will develop where the bacteria entered the body. These chancres are usually painless and this is one of the first signs of syphilis in the mouth.

As the symptoms of syphilis look like many other conditions, including a pimple, it can be a bit difficult to spot oral syphilis. Infected people may not have symptoms and signs are usually mild. There are 4 stages of a syphilis infection, and each stage has different symptoms.

Primary syphilis

In this stage, infected people develop chancre (sore) it can be inside the mouth, on the lip, or on the tongue. This lasts 3 to 6 weeks and it may heal on its own. Infection is spread when direct contact with a sore happens. It may occur during sexual activity or oral sex. Proper treatment will prevent this infection from moving to the next stage.

Secondary syphilis

The secondary stage begins in 6 weeks to 6 months after exposure and this stage may last up to 3 months. Symptoms may include:

  • White patches inside the mouth
  • Rash on palms of the hands and the bottom of feet, or over the whole torso
  • Swollen lymph nodes
  • Fever
  • Large or raised sores on mucous membranes, such as gums or tongue
  • Sore throat
  • Headaches
  • Weight loss

Latent syphilis

In this stage, infected people do not have any noticeable symptoms. And this stage lasts for years and the person who is infected will continue to have syphilis even though there are no symptoms.

Tertiary syphilis

Tertiary syphilis can be life-threatening and can occur years or decades post the initial infection. Nearly 15% to 30% of people who left the syphilis untreated enter this stage. As this stage can affect many organs, symptoms vary depending on the organs affected. Symptoms may include:

  • Brain damage
  • Heart disease
  • Neurological disorders
  • Personality changes
  • Inflammation in the blood vessels
  • Memory loss
  • Blindness
  • Deafness

Oral syphilis testing

The doctor or dentist will draw blood or take a fluid sample from the sore for testing. Nontreponemal and treponemal tests are used to diagnose the infection. Both the tests together can confirm a diagnosis of syphilis. Sometimes, a biopsy of tissue or fluid is used to diagnose oral syphilis. This helps the doctors to see the bacteria under a microscope.

Who should test for syphilis routinely?

  • Any person who lives with HIV
  • Any person who is taking PrEP for HIV prevention
  • Sexually active men (MSM)
  • Pregnant women
  • Sex worker
Oral Syphilis Symptoms
Oral Syphilis Symptoms

Oral syphilis treatment

Oral syphilis is treatable in the early stages. Treatment for oral syphilis is the antibiotic benzathine penicillin G. In the primary & secondary stages, the treatment includes one injection of antibiotic. For the other stages, the dose of the antibiotics is the same but multiple injections are required. It’s essential for a person to complete treatment when they are diagnosed with oral syphilis. Usually, sores go away on their own in a few weeks without treatment. However, it does not mean the infection is gone. The bacteria can still be the body and can cause additional symptoms later. When this condition is left untreated it can cause long-term damage to other organs, like the heart and brain.

A pregnant woman who is allergic to penicillin can undergo desensitization, which helps them to take drugs safely. An infected person needs to notify their partner, so they can be tested and treated if necessary. Apart from this treatment, it is important to abstain from sexual contact with new partners until the sores are completely healed. The doctor may recommend a blood test every 6 months for a year to confirm that the bacteria is no longer present in the blood.

Treatment is important because untreated syphilis may lead to long-term serious complications like organ damage and failure.

Side effects of oral syphilis treatment

After treatment infected people may experience:

  • Fever
  • Chills
  • Headaches
  • Joint or muscle pain
  • Nausea

These side effects only last about 24 hours. After treatment, the antibiotics will kill the bacteria that cause syphilis and prevent additional problems from occurring.

Is Syphilis curable?

Syphilis can be cured with antibiotics. Syphilis is curable even in the later stage. However, treatment can’t repair or reverse any damage that has already occurred, but it prevents further damages.


Usually, syphilis is easily treated with antibiotics. But when an infected person doesn’t get treated, the infection can lead to a number of serious even life-threatening conditions. They may include blindness, heart disease, nervous system disorders, mental disorders, and aortic aneurysms.

  • When a person has syphilis, they’re up to 5 times more likely to get HIV. Syphilis sores can be open, making it easy for HIV to get into the body during sex.
  • Small bumps or gummas may develop on skin, bones, or in any organs and it destroys the tissue around them.
  • Syphilis can cause problems with the nervous system. Symptoms may include severe headache, stroke, loss of muscle coordination, paralysis, or inability to move part of the body, and a mental disorder called dementia or even blindness or changes to vision.
  • Cardiovascular problems may include bulging and inflammation of the aorta and may also damage heart valves.

Syphilis and HIV

It was estimated that in the US nearly half of MSM with primary and secondary syphilis were also living with HIV. According to a 2020 study of 4,907 HIV-positive individuals, it was identified that repeat syphilis infections increased over 11 years of follow-up. Factors that are associated with repeat syphilis in this study included:

  • Younger age
  • Being assigned male at birth
  • Having a previous history of STIs

Having an STI, particularly the one which causes sores, makes it easier for HIV to get into the body. When a person has been diagnosed with syphilis they should also test for HIV. People with HIV are more likely to get syphilis. Especially in the case of people who don’t get treated or who have a lower CD4 count. Syphilis infection may also progress more quickly in people living with HIV, so it’s important to get tested and treated early.  If left untreated, syphilis can cause serious health problems like neurosyphilis. Due to HIV’s impact on the immune system, it makes syphilis harder to treat.

Treatment in the early stages of syphilis involves a single injection of the antibiotic penicillin. And in later stages, it involves additional injections or a course of intravenous (IV) antibiotics. As having HIV is associated with the potential risk of ineffective syphilis treatment, follow-up is essential. This may involve repeated syphilis blood tests in the months after treatment to verify that treatment was effective.

Syphilis and pregnancy

Syphilis can be passed from infected mothers to their children during pregnancy (congenital syphilis). All pregnant women are advised to get tested at their first antenatal appointment, and after any time that they think they were at risk of getting syphilis. Antibiotics are prescribed to cure the infection. If left untreated it may cause serious health problems to the mothers as well as their infants.

  • Miscarriage is a condition where a baby dies in the womb before 20 weeks of pregnancy.
  • Premature birth is when birth happens too early (before 37 weeks of pregnancy).
  • Fetal growth restriction is when a baby doesn’t gain weight.
  • Low birth weight, when babies are born weighing less than 5 pounds, 8 ounces.
  • Problems with the placenta and the umbilical cord. The placenta grows in the uterus and supplies the baby with food and oxygen through the umbilical cord. During congenital syphilis, the placenta grows large and the umbilical cord becomes swollen.

Penicillin G is an effective antimicrobial for treating fetal infection and preventing congenital syphilis. But the evidence is not sufficient to determine the optimal penicillin regimen during pregnancy. Tetracycline & doxycycline must be avoided in the second and third trimesters of pregnancy. There are no alternatives to penicillin for the treatment of syphilis during pregnancy. A pregnant woman who is allergic to penicillin can undergo desensitization, which helps them to take drugs safely.


It’s still possible to get the infection again even after the treatment. So, it’s essential to follow preventive measures to reduce the risk of syphilis infection.

  • Avoid having intimate contact with an infected person
  • Use a condom or dental dam
  • Be in a mutually monogamous relationship
  • Get regular tests for STDs

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