Syphilis is a highly infectious bacterial infection caused by the bacterium Treponema pallidum. It is spread primarily through sexual contact, however, the infection can also be passed from mother to fetus during childbirth causing congenital syphilis in the infected offspring. Syphilis is unique among sexually transmitted infections (STIs) in that its symptoms vary dramatically depending on the individual’s stage of infection. Once a life-threatening infection, syphilis’ symptoms have become much more manageable in modern times due to the widespread availability of medical treatments and the decreasing capability of the Treponema pallidum virus to invade host tissues. Inventions such as the condom and the dental dam have also significantly decreased the spread of this infection. 


If left untreated, syphilis will progress through four stages of infection: primary, secondary, latent, and tertiary or late stage. Each stage is characterized by a shift in the appearance of the infection’s symptoms. However, it should be noted that the stages may overlap, symptoms may dissipate, or symptoms may be confused with something entirely different.

Primary Stage

A bump on a tounge.

The primary stage of syphilis is the first to occur and is typically acquired from direct contact with another individual’s infectious lesions. The primary stage is characterized by the appearance of a single, firm, usually painless, non-itchy skin ulceration called a “chancre.” The chancre may appear anywhere between 10 to 90 days, but on average, three weeks after exposure to the bacterium. The chancre will appear where the infection entered your body. Potential locations for the chancre to appear are on the vulva, vagina, anus, penis, scrotum, and rarely, the lips or mouth.1 Due to the chancre’s painless, non-itchy nature, it may easily be mistaken for an ingrown hair or for another type of sore. However, the chancre is highly contagious. Appearance of multiple chancres is rare, nonetheless, this is more commonly observed in patients who are also infected with HIV. Syphilis conditions tend to exacerbate HIV symptoms. This is problematic due to the infectious nature of the sore. Chancres will heal on their own with or without medication. This takes roughly three to six weeks.2 However, without medication, the body is only curing the chancre. Syphilis will remain to proceed into the secondary stage. 

Secondary Stage

A spread out red rash on a person's upper body.

The secondary stage of syphilis may last one to three months and begins between six weeks to six months after exposure.4 The secondary stage is acknowledged by the development of a rash that encompasses the entire body. The rash will begin at the site of the chancre and may cover an individual’s body including the hands and feet. This rash is usually not itchy and may be accompanied by wart-like sores in the mouth or genital area.2 Additionally, individuals may experience flu- like symptoms such as muscle aches, fever, sore throat, and swollen lymph nodes. These symptoms may come and go for the duration of up to two years. Much like the chancre, the symptoms will heal themselves. However, once again, this is not curing the inherent infection. The only cure for syphilis is medication prescribed by a medical professional.  

Latent Stage

During the latent phase, the infection will progress to a completely asymptomatic stage (hidden stage). The latent stage may last for years, and symptoms may never return, or the disease can progress to its final and most harmful stage. The latent and tertiary stages of syphilis are not transmissible.

Tertiary or Late Stage

The tertiary stage (final stage) of syphilis affects between 15 to 30 percent of people with syphilis who do not receive treatment. Usually occurring years after the initial infection, tertiary syphilis is life-threatening. At this stage, the disease is not infectious, but the damage inflicted upon the individual is permanent. Serious health complications due to final stages of syphilis include: severe problems with the heart, brain, and nerves that can result in paralysis, blindness, dementia, deafness, impotence, and even death. These problems may occur years, or possibly decades, after the original, untreated infection.4

Diagnosis & Treatment

Syphilis can easily be tested for through a simple blood test. A full STI screening will indicate potential infections. Syphilis is easily curable with antibiotics in the early stages. If you’ve been infected with syphilis for less than a year, a single dose of penicillin is usually enough to destroy the infection. For those allergic to penicillin, tetracycline, doxycycline or another antibiotic can be given instead. If you are in a later stage of the disease, more doses will be needed.4 Sexual partners of people with syphilis should be tested and, if necessary, treated. After treatment, patients are typically asked to have periodic blood tests to ensure a continued appropriate response to the usual dosage of penicillin. Patients are also advised to avoid sexual contact with others until the completion of treatment and blood tests verify the absence of infection.

Blood tests can confirm an important symptom of syphilis: the presence of particular antibodies that the body produces to fight infection. In addition, a doctor may scrape a small sample of cells from a sore and have them analyzed by microscope in a lab. This test can only be performed during primary or secondary syphilis, when sores are present. The scraping can reveal the presence of bacteria that cause syphilis. If it is suspected that an individual has any nervous system complications resulting from syphilis, his or her doctor may also suggest collecting a sample of cerebrospinal fluid through a procedure called a lumbar puncture, or spinal tap. Methods of treatment differ significantly depending on whether the individual has early- or late-stage syphilis. For early infections (less than one year), the favorable treatment would be a single dose of intramuscular penicillin G or an oral dose of azithromycin. Alternatively, doxycycline or tetracycline may be used, but they are not preferred for pregnant females due to the health risks they pose to the fetus. Syphilis has been observed to develop resistance to certain antibiotics, including clindamycin and rifampin.2

Late-stage syphilis involving infection of the nervous system is typically treated with very heavy doses of intravenous penicillin for a minimum of 10 days. If the infected individual is allergic to penicillin, ceftriaxone may be used instead. Other late presentations of syphilis may be treated with weekly administration of intramuscular penicillin G for a duration of three weeks. Treatment of late-stage syphilis limits any further progression of the illness, but does little to ameliorate the damage that has already occurred.2

The first day of treatment might be accompanied by a day-long condition known as the Jarisch-Herxheimer reaction; symptoms of the Jarisch-Herxheimer reaction include fever, chills, nausea, achy pain, headache, and tachycardia. These side effects usually start an hour after treatment begins and are caused by cytokines (signaling proteins) released by the immune system in response to compounds left from rupturing bacteria.2

Congenital Syphilis

Red rashes on a baby's cheeks.

In addition to the typical staged progression of syphilis, congenital syphilis (syphilis passed from mother to child during pregnancy or childbirth) manifests in a separately unique fashion. Infants with congenital syphilis do not typically have symptoms at first, but the disease may progress to include a rash, deafness, teeth deformities, and collapse of the bridge of the nose.2 Pregnant women are advised to get tested for syphilis. 


Syphilis is spread from sexual contact with someone who has it. The infection can be passed even without the transmission of bodily fluids. Syphilis is spread during vaginal, anal, or oral sex. Because of the often asymptomatic stages of syphilis, having no noticeable symptoms, using a condom or a dental dam are the best preventive measures. If sexually active, regular STI screening at your local clinic is advised. Due to syphilis’s large array of symptoms a blood test is the only reliable method to diagnose whether or not an individual has contracted the infection. In light of the fatal effects syphilis can have on unborn children, health officials recommend that all pregnant women be screened for the infection. Additional risk factors that may increase the likelihood of contracting an STI are: 

  1. Engaging in unprotected sex.
  2. Multiple partners increases the likelihood that one of them is a carrier of disease.
  3. Unprotected anal sex is the riskiest form of sex and the most likely to transmit an STI.
  4. Having HIV, because compromised immune system increases one’s risk of contracting infection.

Prevalence and Statistics

In 2017, a total of 30,644 cases of primary and secondary (P&S) syphilis were reported in the United States, yielding a rate of 9.5 cases per 100,000 population.3 Rates of syphilis infection have been increasing over the past three decades. Ninety percent of cases occur in developing nations. The infection affects between 700,000 and 1.6 million pregnancies a year, resulting in spontaneous abortions, stillbirths, and congenital syphilis. Syphilis increases the risk of HIV transmission by two to five times and co-infection (infection by both viruses) is common. If left untreated, syphilis has a mortality rate of 8% to 58% with a greater death rate in males. The symptoms of syphilis have become less severe throughout the 19th and 20th centuries partly due to widespread availability of effective treatment and decreasing virulence of the bacterium. Rates in the United States are currently six times greater in men than women and seven times greater in African Americans than Caucasians. More than 60% of cases in the United States are among males who have sex with other males.3

Concluding Remarks 

While syphilis is no longer the life threatening disease it once was, rates of transmission have been increasing in recent years. With the widespread availability of condoms, dental dams, and cheap effective STI screening, syphilis is easily preventable and curable. Due to the increased rates of transmission, it is imperative that anyone who is sexually active practices safe sex. This includes the use of condoms—male or female— and dental dams. It is highly recommended to have regular STI screening in addition to safe sex practices. Here are guidelines one should follow if they or their partner believe to have contracted an STI:

  • Do not immediately blame your partner for the infection. One or both of you might have unknowingly been infected by a previous partner.
  • Be honest with health care workers. They are there to help you – not to judge you. Any misinformation could halt the progress of your recovery and treatment.
  • Contact your local health department. They may not have the staff and funds to offer especially comprehensive services, but they likely maintain STI programs that provide confidential testing, treatment and partner services.

At worst, syphilis is a life threatening disease if left untreated. However, with modern medicine and the ease of treatment with antibiotics, syphilis is easily manageable. 


  1. Parenthood, P. (n.d.). What Is Syphilis & How Do You Get It? Retrieved May 13, 2019
  2. Syphilis. (2019, January 16). Retrieved May 13, 2019
  3. Syphilis – 2017 Sexually Transmitted Diseases Surveillance. (n.d.). Retrieved May 13, 2019
  4. Syphilis: What Is It? What Causes You To Get It? Is It Curable? (n.d.). Retrieved May 13, 2019

Last updated 14 May 2019.