Syphilis goes through several different stages. While the stages have different symptoms, syphilis may not cause noticeable symptoms or even any symptoms at all.
Primary Syphilis: The main symptom is a painless sore, called a 'chancre'. It will appear on your cock, balls, mouth, throat or arse, turn into a scab and then heal. It usually takes 3 weeks after infection for the sore to develop, but it can take up to 3 months. You may not even notice it. This stage is very infectious. If left untreated the sore will disappear after a few weeks, but the infection will progress.
Secondary Syphilis: Symptoms can include a rash on the body (often on the palms and soles of feet), patchy hair loss, fever, enlarged lymph nodes ("swollen glands") or a general feeling of being unwell. These symptoms usually show up 2 to 12 weeks after infection, but can take up to 6 months. You may not notice these symptoms either. There is also the chance at this stage for syphilis to infect major organs (e.g. liver, brain, kidneys). This stage is very infectious.
Latent Syphilis: This is a hidden stage, where the person is infected with syphilis but doesn't have any symptoms. Syphilis can still be passed on to other people during this stage.
Tertiary Syphilis: This is the stage in which syphilis has infected major organs, like the heart or brain. It can cause permanent damage and very serious complications. For example, in the heart, syphilis can damage the aorta and heart valves. In the brain (known as neurosyphilis), it can cause many symptoms, from headaches and dizziness to dementia and changes in personality. It can also infect the nerves, causing blindness, deafness, paralysis or even death.
While tertiary syphilis usually takes years to develop, syphilis can sometimes affect major organs early on. Neurosyphilis can occur at any stage of syphilis infection. People living with HIV who have been infected with syphilis are at higher risk of developing neurosyphilis than those who are HIV-negative.