Is Syphilis Contagious?

Syphilis is a highly contagious sexually transmitted infection (STI) that is caused by bacteria. The first symptom of the infection is a single or multiple sores in the area where the bacteria entered the body, typically near the genitals. Other symptoms include a rash on the hands or soles of the feet and flu-like symptoms, such as fever, fatigue, and muscle aches, as well as hair and weight loss.

This article reviews when syphilis is most contagious, how it spreads, and what can happen if a person delays or doesn’t get treatment.

Healthcare provider consults with person who may have syphilis

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When Is Syphilis Highly Contagious?

There are four stages of a syphilis infection: primary, secondary, latent, and tertiary.


The first stage of syphilis comes right after a person contracts the bacteria and presents with single or multiple sores. The sores last for roughly three to six weeks and heal with or without treatment. The infection, however, is still ongoing even after the sores heal.


The secondary stage occurs when the initial sore has either finished healing or during the late stage of healing. During this stage, a body rash can appear on the soles of the feet or the palms of the hands.

The other symptoms of syphilis previously mentioned may also develop during this stage. Like the primary stage sores, these signs of infection will go away with or without treatment. Without treatment, the infection will go into latency.


During the latent stage, there are no symptoms, but the infection is still present within the body. This latent stage can last for years without treatment. It's difficult to determine if a person has syphilis during this time because they are asymptomatic.


If left untreated, people with syphilis may go on to develop the tertiary stage symptoms. This final and most dangerous stage of syphilis is marked by infection of other organ systems. The heart, brain, and nervous system can all be affected during the tertiary stage, which leads to more severe infections that can be life-threatening.

When Is Syphilis Most Contagious?

The most contagious stages of syphilis are primary, secondary, and early latency. Since these stages typically occur within 12 months of the initial infection, the first year after infection is considered to be the most contagious time. While it is incredibly rare, passing on syphilis during a late-latent and tertiary infection period can occur.

How Syphilis Spreads

Syphilis is considered an STI, which means that it is primarily spread through sexual contact with a person who has the infection.

Oral, anal, or vaginal sexual intercourse is how most cases of syphilis are spread. The second-most common mode of spreading syphilis is when pregnant mothers with the infection pass it to their unborn babies.

In rare cases, syphilis can be spread in other ways, such as:

  • Blood transfusions
  • Organ donation
  • Biting in nonsexual and sexual situations
  • Feeding prechewed food to infants from an infected person’s mouth

Can Kissing Spread Syphilis?

If you have a syphilis sore in your mouth and kiss another person, you can spread the infection to others. However, kissing is not a typical method of transmission.

How Long Does Syphilis Last After Treatment?

Syphilis is a curable infection that is treated using antibiotics. A person will be required to take antibiotics for up to two weeks. Injectable antibiotics are also sometimes used for syphilis treatment if a person can tolerate penicillin.

During treatment, people must refrain from any activities that may pass on the infection for the entire duration of treatment. Once treatment has stopped, it can take up to two weeks for the syphilis bacteria to be fully cleared from the body.

Can You Pass Along Syphilis During Treatment?

Syphilis can be transmitted at any time during the early stages of infection, treatment, and for as long as two weeks following the end of treatment. 

Complications If Left Untreated

If a person doesn’t know they have syphilis and it goes untreated for a long time, they could end up in the tertiary stage. This stage can cause permanent damage to organs, including the brain, heart, and liver. Additionally, the eyes and ears can also be affected.

When the brain is affected by a syphilis infection, it can cause a decline in a person's cognition. This results in difficulties with focus, memory, and thinking. In more severe cases, dementia (loss of cognitive functioning) can be brought on by syphilis.

Some other serious complications include:

  • Blindness and vision changes
  • Vertigo and dizziness
  • Loss of hearing
  • Tinnitus, which is marked by ringing, buzzing, or roaring in the ears
  • Issues with muscle movement
  • Personality changes
  • Severe headaches
  • Lesions form on the skin, bones, and inside organs
  • Cardiovascular disease

Although neurological problems (affecting the brain and nervous system) are typically associated with the later stages of the disease, they can occur at any point in the infection.

Syphilis Prevention

The best way to prevent contracting syphilis is through safer-sex practices. This could include getting tested regularly and always using condoms properly. Avoiding sexual intercourse with someone who has an active infection or any sores will also keep it from spreading.


Syphilis is a highly contagious sexually transmitted infection that starts with single or multiple sores in the area of transmission. As the disease progresses through the rest of the stages (secondary, latent, and tertiary), other symptoms may develop.

The secondary stage presents with flu-like symptoms, such as fever, muscle aches, fatigue, and headache, along with a rash on the hands and feet. The latent stage is marked by no symptoms at all. The tertiary stage can present with more severe symptoms because the health of other organ systems becomes compromised by the infection.

Syphilis can be cured through the use of antibiotic treatments. It's important to test early and often if you notice any sores or are aware of sexual contact with an infected individual. People can avoid long-term complications of the disease, such as dementia, blindness, and hearing loss, through active prevention and prompt treatment.

A Word From Verywell

Though STIs can have a stigma associated with them, remember that they are very common and many are treatable. If you notice any sores after having sexual contact with a new partner, you should see your healthcare provider for testing. Catching syphilis early will help to avoid any long-term health issues that can occur if it is left untreated.

Frequently Asked Questions

  • Can syphilis be transmitted non-sexually?

    Yes. The most common nonsexual way to spread syphilis is from an infected mother to a fetus in the womb. While it is rare, there have been cases of other types of nonsexual transmission of syphilis. Organ donation, blood transfusions, and biting have all been documented as spreaders.

  • Can you get syphilis from kissing?

    Yes, though it is incredibly rare. Kissing is by no means a main method of transmission.

  • How long can you have syphilis without knowing?

    You can have syphilis for decades without knowing that you have it. This is especially true if—when symptoms do arise—you mistake them or brush them off. If left untreated for many years, there is a chance that syphilis will cause permanent damage to organs such as the brain and heart.

  • Is syphilis curable?

    Yes. Syphilis is a highly curable disease. Typically, a person with syphilis can get a round of antibiotic treatment that will cure them of the disease. The type and duration of treatment will depend on what antibiotics a person can tolerate and how long they’ve had the infection.

9 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.
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By Angelica Bottaro
Angelica Bottaro is a professional freelance writer with over 5 years of experience. She has been educated in both psychology and journalism, and her dual education has given her the research and writing skills needed to deliver sound and engaging content in the health space.