What Are the Side Effects of Untreated Syphilis?

Syphilis is a sexually transmitted infection (STI) that goes through four stages: primary, secondary, latent, and tertiary.

If left untreated, syphilis can invade multiple systems in the body and damage organs. This can be life-threatening.

Learn more about the symptoms of syphilis, how it is transmitted, its side effects, complications, and treatment options.

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What Is Syphilis?

Syphilis is a form of STI. It is curable, but if left untreated, it can lead to serious health complications.

The infection occurs in four stages:

  • Primary
  • Secondary
  • Latent
  • Tertiary

The different stages can cause different symptoms. Tertiary syphilis is the most serious stage and can result in a number of complications.

Symptoms of Primary and Secondary Syphilis 

During primary syphilis, symptoms may include a single sore or multiple sores. This may occur on or near the:

  • Anus
  • Penis
  • Vagina
  • Rectum
  • Lips
  • Mouth

Typically, the sores are painless, firm, and round. In primary syphilis, they may last between three to six weeks and heal even without treatment. Treatment is still necessary, though, to prevent progression to secondary syphilis.

In secondary syphilis, rashes and sores may appear on or near the anus, mouth, or vagina.

The rash may be:

  • Reddish-brown
  • Rough
  • Not itchy

Other symptoms that may occur in secondary syphilis include:

  • Headache
  • Fever
  • Weight loss
  • Swollen glands
  • Hair loss
  • Sore throat
  • Fatigue
  • Muscle aches

How It Is Transmitted

Those who are sexually active can get syphilis. It also can be transmitted from an infected mother to her unborn baby.

During oral, anal, or vaginal sex, syphilis spreads through direct contact with a syphilis sore.

Syphilis is not spread through casual contact. This means it can't be contracted through:

  • Sharing clothes
  • Sharing utensils
  • Toilet seats
  • Hot tubs
  • Swimming pools
  • Bath tubs
  • Door knobs

Side Effects and Complications

At any stage, a syphilis infection can invade various systems throughout the body. This can lead to side effects and complications.


Neurosyphilis most commonly occurs in people who have had untreated syphilis for years. It typically occurs 10 to 20 years after the initial infection with syphilis.

It is a bacterial infection of the spinal cord and brain. It is caused by the same bacterium that causes syphilis, Treponema pallidum.

Not everyone with syphilis will develop neurosyphilis.

Neurosyphilis can cause a variety of symptoms:

  • Dementia: This causes behavioral changes or problems with cognition.
  • Meningitis: This is inflammation of the tissues of the spinal cord and brain. It is a life-threatening complication of a syphilis infection.
  • Seizures: The type of seizure can vary.
  • Hallucinations: These may be auditory or visual hallucinations.
  • Tabes dorsalis: This causes abnormal sensations as well as muscle weakness.

Ocular Syphilis

Ocular syphilis occurs when the syphilis infection invades the eye, affecting vision.

Symptoms of ocular syphilis may include:

  • Sensitivity to light
  • Pain in the eye
  • Redness in the eye
  • Seeing spots (called floaters) in field of vision
  • Blurry vision
  • Blindness
  • Changes to vision


Otosyphilis occurs when the syphilis infection invades the vestibular, or auditory (hearing), system of the body.

This can cause a variety of symptoms, including:

  • Dizziness
  • Trouble balancing
  • Vertigo
  • Loss of hearing
  • Tinnitus (a hissing, ringing, buzzing, or roaring sound in the ears)

Cardiovascular Syphilis

Cardiovascular syphilis occurs when a syphilis infection invades the cardiovascular system (the heart and blood vessels).

Cardiovascular syphilis can cause a variety of symptoms, including:

  • Inflammation of the aorta
  • Aortic valve insufficiency (when the heart valve doesn't open properly)
  • Narrowing of the coronary arteries
  • Aortic aneurysm (a bulge in the aorta that may rupture)
  • Obstruction of the coronary arteries

Gummatous Syphilis

During late-stage syphilis (tertiary syphilis), growths similar to tumors can form. These are called gumma and are swollen or dead tissue.

They are caused by the same form of bacterium that causes the syphilis infection. Most commonly, they occur on the liver but may also appear on the:

  • Skin
  • Heart
  • Brain
  • Bone
  • Testes
  • Eyes

Congenital Syphilis

In congenital syphilis, the infection is passed from mother to the fetus in the uterus. This happens when the mother contracts syphilis either prior to pregnancy or during pregnancy.

It is more common for infection to be passed on if the mother is infected during pregnancy, however, infection can still be transmitted from a mother infected prior to pregnancy.

Symptoms of congenital syphilis do not always appear immediately at birth and may take weeks, months, or years following birth to develop.

Early congenital syphilis may cause symptoms between the ages of 3 and 14 weeks, but can also occur up to the age of 5.

Possible symptoms include:

  • Low birth weight
  • Rash
  • Inflammation of the umbilical cord
  • Fever
  • High cholesterol levels at birth
  • Anemia
  • Jaundice
  • Enlarged spleen or liver
  • Rhinitis
  • Hair loss

Late congenital syphilis may cause symptoms after the age of 5. Some people may be undiagnosed even into adulthood.

Possible symptoms include:

  • Pain in bones
  • Eye pain
  • Blurred vision
  • Abnormal level of sensitivity to light
  • Prominent, bony forehead
  • Fissuring (splitting or cracking) around the anus and mouth

How to Test for Syphilis

In the majority of cases, a blood test is used to test for syphilis. Sometimes fluid taken from a syphilis sore is also tested.

If you have symptoms that indicate syphilis, you should be tested. Your sexual partners should also be tested.


Syphilis can be successfully treated with antibiotics. However, this won't be able to reverse the damage already done by the infection.

Even after treatment, it is possible to get syphilis again.

How to Prevent the Risk of Infection

The only way to totally prevent syphilis is by not having sex of any kind. This includes vaginal, anal and oral sex.

If choosing to be sexually active, risk can be reduced by:

  • Having sex only with a long term monogamous partner who does not have syphilis
  • Using condoms correctly every time you have sex


Syphilis is a sexually transmitted infection that occurs in four stages: primary, secondary, latent, and tertiary. It can be spread through sexual contact or from an infected mother to a fetus or baby during birth. If left untreated, the infection can impact multiple systems and organs in the body. This can be life-threatening. Syphilis can be treated with antibiotics, but this will not treat any damage already caused by the infection.

A Word From Verywell

Having an STI can be uncomfortable. If you have symptoms that indicate syphilis, it is important to reach out to a healthcare provider. They can provide testing and treatment that will help prevent dangerous complications.

Frequently Asked Questions

  • What does syphilis look like?

    Syphilis may take on a different appearance depending on the stage of the infection. In primary syphilis, you may get sores that are firm and round.

    In secondary syphilis, a rash may also appear that is red, reddish brown, or rough looking.

  • What are the four stages of syphilis?

    Syphilis has four stages:

    • Primary
    • Secondary
    • Latent
    • Tertiary
  • Is there a cure for syphilis?

    A syphilis infection can be successfully treated with antibiotics, but this will not repair any lasting damage caused by the infection.

  • Does syphilis reduce your life expectancy?

    If left untreated, syphilis can impact multiple organs and systems within the body. This can be life-threatening.

  • How long does it take to get rid of syphilis?

    Length of treatment varies based on the stage of the disease. Tertiary syphilis may require a longer treatment period than primary syphilis.

    Treatment may be required for weeks or longer.

11 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Centers for Disease Control and Prevention. Syphilis – CDC fact sheet,

  2. MedlinePlus. Neurosyphilis.

  3. Meza K, et al. Rapidly progressive dementia as a manifestation of neurosyphilis: case report. Neurology Apr 2017, 88 (16 Supplement) P6.310;

  4. Mount Sinai. Syphilitic aseptic meningitis.
  5. Nutile L. Neurosyphilis with psychosis as the primary presentation. The American Journal of Psychiatry Residents' Journal. 12 Mar 2021. doi:10.1176/appi.ajp-rj.2021.160304

  6. Medline Plus. Tabes dorsalis.
  7. Centers for Disease Control and Prevention. Aortic aneurysm.

  8. Li Xiangdong et al. Cardiovascular syphilis-associated acute myocardial infarction, Medicine: February 19, 2021 - Volume 100 - Issue 7 - p e24788 doi:10.1097/MD.0000000000024788

  9. MedlinePlus. Gumma.

  10. NORD. Congenital syphilis.

  11. NHS. Treatment - syphilis.