Syphilis can cause tinnitus: when it infects the inner ear, a complication called otosyphilis, it typically brings sensorineural hearing loss, tinnitus or vertigo, and antibiotic treatment can sometimes recover hearing that untreated otosyphilis can damage permanently.
It is uncommon and easy to miss: it can arrive before any other sign of syphilis, and it looks like more familiar ear conditions. Unlike most causes of tinnitus, the underlying infection has a specific treatment, and timing matters.
What otosyphilis is
The US Centers for Disease Control and Prevention (CDC) describes otosyphilis as an infection of the cochleovestibular system — the hearing and balance organs of the inner ear — with Treponema pallidum, the bacterium that causes syphilis. Its guidance makes four points that shape everything else here:
- It can occur at any stage of syphilis, not only years into an untreated infection.
- It may be the first sign that someone has syphilis at all.
- The hearing loss can be in one ear or both, can start suddenly and can progress rapidly.
- It can result in permanent hearing loss.
The CDC also notes that people with otosyphilis may have signs of ocular syphilis or neurosyphilis, particularly involving the eighth cranial nerve, the nerve of hearing and balance.
How the bacterium damages the ear is not fully worked out. A 2020 literature review describes two proposed routes: spirochaetes invading the inner ear's fluid directly, or reaching it from the fluid around the brain and spinal cord. Long-standing untreated infection can also affect the surrounding bone and the middle ear's tiny bones.
How it shows up: hearing loss first, tinnitus often with it
Hearing loss is the main presenting symptom, and tinnitus is common alongside it. The published numbers vary with who was counted:
- A 2025 scoping review in The Laryngoscope gathered 57 studies covering 222 patients: hearing loss was reported in 65%, tinnitus in 43% and vertigo in 24%.
- A Thai series of 85 patients, seen between 1984 and 2000, found hearing loss in 90.6%, tinnitus in 72.9% and vertigo in 52.9%.
- A Seattle clinic series of 12 patients seen over ten years found tinnitus in nine and vertigo in two. Seven had audiogram-confirmed hearing loss in both ears.
The 2020 review notes that people who notice a problem in one ear may turn out to have hearing loss in both on a formal hearing test, which is one reason an audiogram is part of the workup. How to read your audiogram explains what the test shows.
The same review warns that otosyphilis mimics other conditions. Its tinnitus and vertigo can resemble Ménière's disease, and its hearing loss can be confused with an acoustic neuroma, autoimmune inner ear disease or stroke. The review says there is no one classic presentation: hearing loss in both ears can be symmetrical or not, mild or moderate, and at low or high pitches.
One gap is worth stating plainly. No study found for this article measured how often syphilis turns out to be the cause when someone's only symptom is tinnitus and their hearing test is normal.
How common it is
Otosyphilis is uncommon, and the counts are probably low.
- US surveillance. A CDC analysis of 2019 national data from 16 jurisdictions with complete reporting covered 41,187 syphilis cases. Ear involvement was reported in 166 (0.4%). The authors say these figures are likely an underestimate because of under-reporting. Reported ear involvement was highest in people aged 65 or older (1.2%) and people who inject drugs (1.6%), and was similar whatever a person's HIV status.
- Symptoms people report. The 2020 review cites a review of 573 people with syphilis in King County, Washington, in which 3.9% reported hearing loss and 2.7% had tinnitus.
- Symptoms people do not report. A 2020 study gave portable hearing tests to 329 people with syphilis who were enrolled in research on spinal fluid abnormalities. 166 (50.5%) had normal hearing, and the rest had loss at low frequencies, high frequencies or both. Loss was more likely in people with bacterial DNA detectable in their blood, with inflammatory cells in their spinal fluid, and with older age. That study cannot say how much of the loss syphilis caused. The 2020 review warns that age-related or noise-related hearing loss in someone with syphilis can be wrongly labelled as otosyphilis.
The background numbers have moved. A 2025 JAMA review reports that US syphilis cases rose by 61% between 2019 and 2023. The CDC's provisional 2024 figures then show primary and secondary syphilis falling for a second year, down 22% from 2023, while congenital syphilis rose for the twelfth year in a row. All 12 patients in the Seattle clinic series presented in the last two of its ten years, and its authors suspect the condition is underdiagnosed.
Who is at risk
Syphilis spreads through contact with infectious sores during vaginal, anal or oral sex, or across the placenta in pregnancy. The JAMA review names people with HIV, people having condomless sex with multiple partners, and men who have sex with men as being at higher risk. In the US data above, around 40% of people with any neurological, eye or ear complication were HIV-negative.
Risk categories are only a starting point. A 2023 case report describes a recently married man in his 50s whose sudden hearing loss in both ears did not improve with prednisone. Only then was he tested, and he turned out to have syphilis and a new HIV diagnosis; he had not at first mentioned past sex with men. The CDC advises that everyone diagnosed with syphilis should be offered an HIV test if their status is unknown or they previously tested negative.
Should people with tinnitus or sudden hearing loss be tested?
The guidance does not line up neatly, and the disagreement is worth seeing whole.
- The CDC: screening for syphilis "should be considered in new onset sensorineural hearing loss, tinnitus, and vertigo".
- The 2020 review goes further, recommending that everyone with new, sudden or fluctuating sensorineural hearing loss be evaluated for syphilis.
- The 2019 US sudden hearing loss guideline makes a strong recommendation that clinicians not order routine laboratory tests in sudden sensorineural hearing loss, citing the lack of benefit of untargeted testing. The sudden hearing loss article covers that guideline in full.
- A Spanish hospital study screened 71 people with sudden hearing loss over six years. Two (2.8%) had positive syphilis antibodies. One had been treated for syphilis years before and did not improve; the other had otosyphilis, and their hearing returned to normal after treatment. The authors concluded that screening is advisable in people at higher risk, such as those with multiple recent sexual partners, or with unusual features such as other nerve problems.
Targeted testing, the middle ground that last study proposes, depends on the clinician knowing about risk. If there is any chance of syphilis exposure, a recent diagnosis, a rash, or a genital or mouth sore, saying so at the appointment is what makes a sensible decision possible. Talking to a doctor who dismisses tinnitus has help with raising the things that feel awkward to say.
How it is diagnosed
There is no single test for otosyphilis. The 2020 review says the diagnosis rests on hearing abnormalities in someone with current syphilis, after other causes have been ruled out.
- Blood tests. The 2023 case report explains that syphilis testing uses two kinds of blood test, treponemal and nontreponemal, together. Treponemal tests can stay positive for life, so a past, treated infection can complicate the picture.
- A hearing test and an ENT assessment. The CDC says otosyphilis should be managed together with an otolaryngologist (an ear, nose and throat specialist).
- Spinal fluid. For someone whose only symptoms are in the ear, whose neurological examination is normal and whose blood tests are positive, the CDC says a spinal fluid examination is likely to be normal and is not recommended before treatment.
How it is treated
The CDC's 2021 STI treatment guidelines say otosyphilis should be treated with the same regimen as neurosyphilis. The recommended regimen is aqueous crystalline penicillin G, 18–24 million units a day, given intravenously for 10–14 days. If adherence can be ensured, an alternative is daily procaine penicillin injections into the muscle plus probenecid tablets, both for 10–14 days. The guidelines describe ceftriaxone as an option for people allergic to penicillin, but with limited supporting data.
That regimen is not the one most people associate with syphilis. The JAMA review gives the standard treatment for early syphilis as a single injection of benzathine penicillin. With otosyphilis, the ear symptoms change which regimen applies.
Steroids are common and unproven. The 2020 review explains that steroids are often added to calm inflammation and to prevent a Jarisch-Herxheimer reaction, a reaction to starting antibiotics that can make hearing symptoms worse. The CDC guidelines say that although steroids are used frequently for otosyphilis, they have not been proven to help.
The evidence behind all of this is thin. The 2020 review found no randomised controlled trials of otosyphilis treatment, and the 2025 scoping review says there is no formal consensus on managing it. The regimen is borrowed from neurosyphilis.
Does hearing come back, and does the tinnitus?
Sometimes, and earlier treatment appears to help.
- Published cases. Of the 222 patients in the 2025 scoping review, 84 had an outcome recorded. 48 (57%) improved, 14 (17%) improved partly and 22 (26%) did not improve. In the 30 cases that recorded it, symptoms had lasted 6.6 weeks on average.
- The same authors' hospital series. Of 13 patients followed up, six recovered fully, two partly, four needed further treatment and one did not improve. People who came to care after more than a year of symptoms were more likely to recover incompletely.
- The Thai series. Hearing was improved or stable in 93.4% at short-term follow-up and 83.3% longer term. "Stable" is not recovery. The 2020 review also notes that 11% of that group had a blood test result suggesting their syphilis was no longer active.
- The 2020 hearing study. Among 33 people retested after treatment, hearing was less likely to return to normal in older people, and less likely to return to normal at high pitches when the loss was more severe or the spinal fluid showed inflammation.
Treatment does not guarantee recovery. In the man from the 2023 case report, the vertigo and the hearing in one ear improved, but hearing in the other ear did not return. A hearing aid helped, and he still needed medicine for vertigo from time to time.
These figures come from case reports and small series, and the scoping review's authors say that including so many individual case reports brings bias and limits how far the results can be generalised.
On tinnitus specifically, the evidence is silent. None of the studies above reports tinnitus outcomes separately from hearing. Where tinnitus persists alongside lasting hearing loss, it is managed as other tinnitus with hearing loss is: hearing aids where hearing loss is the driver, sound therapy, and CBT for the distress it causes.
When to get seen
- Hearing that drops over hours or days is urgent whatever the cause. Get seen the same day if you can. The when to seek care tool sorts which symptoms need that speed.
- If you have been diagnosed with syphilis, or may have been exposed, and notice new tinnitus, hearing loss or dizziness, tell the clinic treating you. Ear symptoms change the treatment.
- If ear symptoms come with vision changes, severe headache, facial weakness or confusion, say so at once. The scoping review found visual disturbance in 9.0% of published patients and facial weakness in 5.4%.
- If you are being investigated for sudden hearing loss and syphilis is a possibility, mention it even if nobody asks. How tinnitus is diagnosed sets out the wider assessment, and Lyme disease and tinnitus covers another infection where the same question about testing comes up.