Untreated syphilis can lead to serious health complications such as damage to the brain and nervous system (neurosyphilis) or to the eye (ocular syphilis). These health complications usually occur 10-30 years after primary infection.
Symptoms of neurosyphilis include
severe headache;
difficulty coordinating muscle movements;
paralysis (not able to move certain parts of your body);
numbness; and
dementia (mental disorder)