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Primary syphilis in Adult
See also in: Anogenital,Oral Mucosal Lesion
Other Resources UpToDate PubMed

Primary syphilis in Adult

See also in: Anogenital,Oral Mucosal Lesion
Contributors: David O'Connell MD, Yun Xue MD, Susan Burgin MD
Other Resources UpToDate PubMed


Syphilis is a sexually transmitted infection (STI) caused by the spirochete bacterium Treponema pallidum. It is characterized by a chronic intermittent clinical course. Treponema pallidum is transmitted person to person via direct contact with a syphilis ulcer during vaginal, anal, or oral sex and may enter through skin or mucous membranes. Hence, the locations for syphilitic ulcers include the vagina, cervix, penis, anus, rectum, lips, hands, and inside of the mouth.

In the primary stage of syphilis, a painless ulceration, or chancre, typically appears about 21 days after initial infection, often preceded by a firm, painless papule. The chancre is easily seen on the frenulum or on the coronal sulcus of the penis, but it may hide under the foreskin. The chancre may be difficult to observe if located in the vagina or on the cervix. The entire genital area is susceptible, including the anus and inside the urethra. Chancres are typically asymptomatic. If secondary erosion or fissuring occurs, they may be painful. Other symptoms may include bloody stool and rectal pain.

Chancres vary in size from a few millimeters to several centimeters. They have an incubation period of 10-90 days (average 21 days). The chancre lasts 3-6 weeks and heals spontaneously.

Follmann balanitis refers to the rare variant of primary syphilis in men that presents with scattered erosions of the glans and foreskin. A primary chancre may be seen in association or may occur before it presents or after resolution.

All patients with primary syphilis will go on to develop secondary syphilis if the condition is left untreated. Secondary syphilis usually appears 3-10 weeks after the primary chancre and is characterized by a papulosquamous eruption and mucosal involvement in some cases. Tertiary syphilis may appear months to years after secondary syphilis resolves and can involve the central nervous system (CNS), heart, bones, and skin.

Ocular screening (eg, slit lamp examination) is advised for patients with suspected or proven syphilis.

Per the US Centers for Disease Control and Prevention (CDC), the majority of reported male primary and secondary syphilis cases where sex of sex partner is known are among men who have sex with men. An increased incidence of syphilis is associated with HIV positivity.

Immunocompromised patient considerations: Genital ulcers caused by syphilis increase the risk of HIV transmission due to epithelial barrier compromise and increased numbers of macrophages and T-lymphocytes with HIV-specific receptors.

HIV infection can alter the clinical presentation of syphilis. Manifestations include multiple chancres, atypical cutaneous eruptions, increased severity of organ involvement (such as hepatitis and glomerulonephritis), and rapidly developing arteritis and neurosyphilis. Neurosyphilis can occur at any stage of syphilis.

Related topics: ocular syphilis, endemic syphilis


A51.0 – Primary genital syphilis

266127002 – Primary syphilis

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Differential Diagnosis & Pitfalls

All patients with a genital ulcer should have serologic testing for syphilis. The following differential will be focused on the chancre of primary syphilis.

  • Genital herpes simplex virus (HSV) – Look for multiple small vesicles on an erythematous base; usually painful. Follmann balanitis can closely resemble HSV.
  • Chancroid (Haemophilus ducreyi) – Multiple nonindurated ulcers with irregular, ragged undermined edges; very painful; yellow exudate commonly present.
  • Lymphogranuloma venereum (Chlamydia trachomatis serovars L1-3) – Ulcers usually not observed but can be small, shallow, and painless; often transient.
  • Granuloma inguinale (Klebsiella granulomatis) – Painless, extensive, and progressive; looks like granulation tissue.
  • Ecthyma gangrenosum – Ulcers are necrotic and rapidly increase, commonly on extremities and trunk.
  • Monkeypox – Lesions beginning in the genital and anal area have been reported.
  • Amebiasis – Starts as a vesicle that ulcerates; typically painful with undermined edges; can have purulent exudate.
  • Erosive candidiasis
  • Genital trauma – Preceded by known insult; erosions are more geometric and painful.
  • Fixed drug eruption – Red-brown papules or annular plaques that are commonly on the penis; can progress to bullae and erosions mimicking syphilis. Recurrent lesions are always located at the same site.
  • Behçet disease – Associated with recurrent oral ulceration, genital ulceration, and ocular abnormalities.
  • Ulcerative genital squamous cell carcinoma
  • Contact dermatitis – Preceded by exposure to irritant; progression to ulceration would be unusual and indicates severe disease.
  • Erosive balanitis – Associated with pain, itch, discharge, and dysuria; more widespread inflammation around ulcers.
  • Calciphylaxis – May rarely present with tender ulceration on genital skin; occurs in patients with renal failure.
  • Pyoderma gangrenosum – The penis is a rare location.

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Last Reviewed:08/24/2020
Last Updated:05/30/2022
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Patient Information for Primary syphilis in Adult
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Contributors: Medical staff writer


Primary syphilis is a disease caused by a corkscrew-shaped bacterium (a spirochete) called Treponema pallidum. It causes disease when it penetrates broken skin of the genitals or the mucous membranes of the mouth or anus. Primary syphilis is usually passed on to others through sexual contact, but other ways are possible (for example, from an infected mother to her newborn baby). There are 3 stages of infection, and it is important to recognize infection in the first (primary) stage, as this stage will heal without therapy. If the infection is not treated early, it will then continue and often goes on to damage the nervous system and the heart, leading to early death.

Syphilis can be completely cured if treated early. Healed infection leaves no immunity, so you can get infected again.

Who’s At Risk

Syphilis occurs worldwide. In the US, the rates of disease are higher in urban areas and the Southern states. Young adults (aged 15-25) are the highest-risk group for syphilis.

Syphilis is more common in men who have sex with men, sex workers, and people exposed to sex workers; this accounts for the fact that syphilis is seen more commonly in men than women.

Signs & Symptoms

Initially, in syphilis, a dusky red flat spot appears at the site of inoculation and is easily missed. Then, a painless ulcer (chancre) appears 18-21 days after initial infection. Genital sites in women affected are the cervix, vagina, vulva, and clitoris. Cervical and vaginal syphilis infections may not be recognized. In men, the chancre is easily seen on the penis. Other locations of infection are limited only by human ingenuity and imagination. Common sites are around the mouth (perioral) and between the buttocks (perianal) areas.

Chancres vary in size from a few millimeters to several centimeters. A chancre is usually painless, solitary, and shallow, with a sharp border and raised, hard edge. About 70-80% of patients have rubbery, non-tender, swollen lymph nodes, often on only one side of the groin, during the first week of infection.

If untreated, the chancre will remain present for 1-6 weeks. If treated, it heals without scarring in 1-2 weeks.

Self-Care Guidelines

Syphilis, in the primary stage, is highly contagious and can heal without therapy, making it easy to be mistaken for something less serious. If you are sexually active and suspect you have been exposed to syphilis or have an ulcer in the mouth, genital area, or anal area, you should seek medical care immediately. You should avoid any further sexual activity and notify any previous sexual partners.

Syphilis can be prevented by abstaining from casual sexual activity and using condoms correctly during any sexual contact. If you are in a long-term relationship, make sure that you know your partner's sexual history or ask that your partner is tested prior to engaging in sexual activity.

When to Seek Medical Care

See your doctor immediately:
  • If you are sexually active and have any ulcer in the genital, mouth, or anal area or suspect you have been exposed to someone with syphilis. Meantime, avoid sexual activity and notify your sexual partner(s) of your illness.
  • If you have had intimate contact with someone with syphilis, have been using intravenous drugs, or if you have engaged in sex with multiple or unknown partners.


Blood and fluid tests will be done to look for other infectious sexually transmitted diseases that are often present along with syphilis.

Antibiotics (penicillin, doxycycline, or tetracycline) will be given, and blood tests will be done again; you will be followed for 2 years to be sure the infection is gone.

Do not engage in sexual activity until the chancre is healed and follow-up blood tests have shown that the infection has been cured.


Bolognia, Jean L., ed. Dermatology, pp.1271-1282. New York: Mosby, 2003.

Freedberg, Irwin M., ed. Fitzpatrick's Dermatology in General Medicine. 6th ed. pp.1263, 2164-2165. New York: McGraw-Hill, 2003.
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Primary syphilis in Adult
See also in: Anogenital,Oral Mucosal Lesion
A medical illustration showing key findings of Primary syphilis : Regional lymphadenopathy, Sexually active
Clinical image of Primary syphilis - imageId=865123. Click to open in gallery.  caption: 'A punched out ulcer with a raised border on the glans.'
A punched out ulcer with a raised border on the glans.
Copyright © 2023 VisualDx®. All rights reserved.