Tertiary syphilis is the most severe and destructive stage of syphilis, developing 10 to 30 years after the original infection in people who were never treated. By this point, the bacteria have been silently present in the body for years or decades, and the damage they cause can affect the heart, brain, bones, skin, and nearly every other organ system. Roughly one-third of people with untreated syphilis will eventually develop these late-stage complications.
How Syphilis Reaches the Tertiary Stage
Syphilis progresses through distinct phases. The first stage produces a painless sore at the site of infection, which heals on its own. The second stage causes rashes and flu-like symptoms, which also resolve without treatment. After that, the infection enters a latent period where there are no outward symptoms at all. During this quiet phase, the syphilis bacteria remain alive in the body, slowly triggering low-level inflammation in tissues and blood vessels.
The bacteria behind syphilis break down collagen, the structural protein that holds tissues together, which helps them penetrate deep into organs. Over years, the body’s own immune response to these bacteria becomes part of the problem. Immune cells attack infected tissue but can’t fully clear the infection, creating a cycle of chronic inflammation and tissue destruction. It’s this immune-driven damage, not a toxin produced by the bacteria, that ultimately causes the organ injury seen in tertiary syphilis.
Gummatous Syphilis: Skin, Bone, and Organ Lesions
One hallmark of tertiary syphilis is the formation of gummas: painless, rubbery nodules that grow from a slow-burning inflammatory process. They most commonly appear on the skin, but they can develop in virtually any tissue, including the bones, joints, liver, and mucous membranes. On the skin, gummas typically show up in small clusters. As they progress, they can break through the skin surface, leaving distinctive punched-out ulcers that drain dead tissue.
Larger gummas are destructive. They can invade deep into underlying tissue, erode bone, and heal with retracted, darkened scars. Under a microscope, gummas contain areas of dead tissue surrounded by immune cells, a pattern called caseating granulomas. Historically, about 15% of people with untreated syphilis developed gummatous disease. The term “late benign syphilis” is sometimes used for this form, though “benign” is misleading when gummas destroy tissue in the face, nasal passages, or skeletal system.
Cardiovascular Syphilis
Cardiovascular involvement is one of the most dangerous consequences of tertiary syphilis, occurring in roughly 30% of untreated patients who reach this stage. The primary target is the aorta, the body’s largest artery. Chronic inflammation of the aortic wall, called aortitis, weakens the vessel over time. This can lead to the aorta ballooning outward (aneurysm formation), the aortic valve leaking blood backward into the heart (aortic insufficiency), or narrowing of the small openings where the coronary arteries branch off the aorta.
Coronary ostial stenosis, the narrowing of those coronary artery openings, is a particularly dangerous complication because it restricts blood flow to the heart muscle itself. Rarer manifestations include gummas forming directly in the heart muscle and inflammation of the coronary arteries. These cardiovascular problems develop silently over years and may first announce themselves as chest pain, shortness of breath, or heart failure.
Neurosyphilis: Brain and Spinal Cord Damage
When syphilis invades the nervous system, it’s called neurosyphilis. While this can technically occur at any stage of infection, the most severe forms appear in the tertiary period. Two classic presentations dominate late neurosyphilis: tabes dorsalis and general paresis.
Tabes Dorsalis
Tabes dorsalis results from damage to the nerve fibers in the spinal cord that carry sensory information. The signature symptom is lancinating pain: sudden, intense stabbing sensations in the legs, back, or face that can last minutes to days. Patients gradually lose the ability to sense where their limbs are in space, a deficit called proprioceptive loss, which affects nearly 60% of patients. This creates a distinctive wide-based, stomping gait where the feet slap the ground because the person can’t feel the floor beneath them.
Other features include loss of reflexes in the lower legs, bladder dysfunction leading to urinary retention and incontinence, and episodes called gastric crises, where severe stomach pain, nausea, and vomiting strike without warning. Progressive joint degeneration and optic atrophy can develop over time, and late stages may bring severe weakness in the legs and problems with involuntary body functions like blood pressure regulation.
General Paresis
General paresis is a progressive form of dementia caused by syphilis directly damaging the brain. It starts subtly with forgetfulness and personality changes, then worsens into severe cognitive decline. Some patients present with depression, mania, or psychosis instead of, or alongside, the memory loss. Physical signs include slurred speech, tremors of the face, tongue, and hands, and muscle weakness. Before antibiotics existed, general paresis was one of the most common causes of psychiatric institutionalization.
Eye and Hearing Involvement
Syphilis can infect the visual and auditory systems at any stage, but these complications deserve attention in the context of late disease. Ocular syphilis most commonly causes inflammation inside the eye (posterior uveitis or panuveitis), though it can affect almost any eye structure. It may also cause optic nerve damage and inflammation of the retinal blood vessels. Without treatment, it can lead to permanent blindness. In some cases, vision changes are the very first sign that someone has syphilis at all.
Otosyphilis attacks the inner ear’s hearing and balance structures. It typically causes sensorineural hearing loss, ringing in the ears, or vertigo. The hearing loss can be sudden, one-sided or bilateral, and may progress rapidly to permanent deafness. Like ocular syphilis, new hearing loss or unexplained vertigo can sometimes be the clue that prompts syphilis testing for the first time.
How Tertiary Syphilis Is Diagnosed
Diagnosing tertiary syphilis involves blood tests for syphilis antibodies combined with evaluation of the specific organs affected. When neurosyphilis is suspected, a spinal tap is performed to test the cerebrospinal fluid. The most reliable single test for neurosyphilis is highly specific but only catches 67% to 72% of cases overall. In tabes dorsalis, the detection rate rises to about 75%, and in general paresis, the test is almost always positive. Because no single test is perfect, doctors combine lab results with a patient’s symptoms and history to make the diagnosis.
Imaging studies play an important role too. Chest imaging can reveal aortic aneurysms or widening of the aorta. MRI of the brain and spinal cord may show areas of damage consistent with neurosyphilis. A full eye exam with specialized equipment is needed when ocular involvement is suspected, and hearing tests help evaluate otosyphilis.
Treatment and What It Can Reverse
The treatment for tertiary syphilis is the same antibiotic that has been used for decades: penicillin, given by injection. For late-stage disease, the standard course involves three weekly injections over three weeks, for a higher total dose than what’s used in early syphilis. Neurosyphilis requires intravenous penicillin, typically given in a hospital setting over a longer course.
The critical question for most patients is how much damage can be undone. The honest answer depends on the type of tertiary syphilis and how far it has progressed. Antibiotics will stop the infection and prevent further deterioration, but neurological damage is often not fully reversible. People with early or asymptomatic neurosyphilis usually return to normal health. Those with tabes dorsalis or general paresis typically improve but don’t recover completely. Cardiovascular damage, particularly to the aorta and heart valves, is structural and may require surgical intervention regardless of antibiotic treatment. Gummatous lesions tend to respond well to treatment, often shrinking significantly once the infection is cleared.
Left untreated, tertiary syphilis can cause permanent paralysis, profound dementia, and death. The gap between the initial infection and the onset of tertiary disease, sometimes decades, makes early detection and treatment of syphilis in its first or second stage by far the most effective strategy for preventing these outcomes.