In the course of a few days or weeks after the infection, small nodules may develop at the entry points of the bacteria (e.g. glans or foreskin, vulva lips, lips, mouth or throat, anus or rectum). As a rule, these nodules are (mostly) painless and will grow to approximately the size of a coin. The thus formed ulcer is clearly delineated and has a hard margin. The ulcer is of a brown-red colour, with a shiny surface and it excretes a clear, highly infectious liquid. More often than not, the neighbouring lymph nodes will swell. All these symptoms will decrease by themselves within several weeks, mostly unnoticed. 

The second stage of a syphilis disease will start within four to ten weeks after infection. The following symptoms may occur:

• Initial fever including fatigue, loss of appetite, head and joint aches, night sweats, lymphoma as well as skin or mucosal lesions 
• Not-itching and not-exuding eczema, sometimes scaling and scabby or lenticular, on the torso, the palms of the hands and soles of the feet in particular 
• Coatings on the tongue and in the oral cavity
• Exuding warts
• Hair loss in patches

Approximately two years after the initial infection, these symptoms will subside and the following stage will be symptom-free.

After years or decades, an untreated syphilis infection may lead to severe damage of the inner organs such as the liver, the heart, the stomach, blood vessels, the skeleton and joints as well as the central nervous system. External symptoms are to be found in the form of rubbery callous lumps which will destroy surrounding tissue if they break open. Some of the untreated patients will suffer from a so-called neuro syphilis that may lead to deafness, visual disorders culminating in blindness, progressive mental decline, and finally to death.