Alternative Names

Lues; Cupid’s disease; Syph

Definition of Syphilis

Syphilis is infection with the bacteria .

Causes, incidence, and risk factors

Syphilis is a sexually-transmitted infectious disease. The bacteria that cause it spread through broken skin or mucous membranes.


The symptoms of syphilis depend on the stage of the disease. Many people do not have symptoms.

Signs and tests

Blood tests can be done to detect substances produced by the bacteria that cause syphilis. The older test is the test. Other blood tests may include and


Antibiotics are an effective treatment for syphilis. The antibiotic of choice is penicillin. The dose and how it’s given (into a muscle or into a vein) depend on the stage of syphilis. Doxycycline may be used as an alternative treatment in individuals who are allergic to penicillin.

Expectations (prognosis)

With prompt treatment and follow-up care, syphilis can be cured.


David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine; Jatin M. Vyas, MD, PhD, Assistant Professor in Medicine, Harvard Medical School, Assistant in Medicine, Division of Infectious Disease, Department of Medicine, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc. – 5/30/2009

Syphilis, secondary on the palms
STDs and ecological niches
Primary syphilis
Late-stage syphilis

ADAM Medical Encyclopedia

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