Both an overactive and an underactive thyroid were linked to tinnitus in national studies from Taiwan: 4.9% of people newly diagnosed with hyperthyroidism developed tinnitus, against 3.2% without it, and people with hypothyroidism had a 1.35-fold higher risk after adjustment.
That makes the thyroid worth checking if you have a diagnosed thyroid condition, or symptoms of one, alongside new or worsening tinnitus — though, as below, the link is an association, and some of it probably runs through anxiety, poor sleep and heart-rate changes rather than the ear itself.
When to see a doctor
See your doctor — within a few weeks, not as an emergency — if you have new tinnitus along with signs of a thyroid problem, such as unexplained weight change, fatigue or its opposite, a fast or irregular heartbeat, or sensitivity to heat or cold. Mention the two together rather than as separate complaints. A simple blood test (TSH, and sometimes T3 and T4) can confirm or rule out a thyroid cause, and it is an easy thing to check relative to some of the more involved causes of tinnitus.
Make the appointment sooner if the tinnitus beats in time with your pulse, because pulsatile tinnitus has causes that need their own workup. Go the same day if your hearing drops suddenly, which is an emergency whatever the cause — sudden hearing loss explains why. And if you are having teprotumumab for thyroid eye disease, report new tinnitus, ear fullness or any hearing change to the treating team promptly (see below).
What the research found
A large, population-based longitudinal study from Taiwan's national health insurance database followed patients newly diagnosed with hyperthyroidism against a comparison group without the condition. Over the study period, 4.9% of the hyperthyroidism group developed tinnitus, compared to 3.2% of the non-hyperthyroidism group — 7.86 against 5.05 cases per 1,000 person-years. After adjusting for age, sex, and other conditions linked to tinnitus (vertigo, insomnia, anxiety and hearing loss), people with hyperthyroidism had a 1.38-fold higher risk of tinnitus (95% CI 1.27–1.50). That is a modestly elevated rate in a dataset large enough to detect a real difference, not just a coincidental pattern in a small sample.
A separate population-based study examining risk factors for tinnitus more broadly, in 19,290 Korean adults surveyed between 2009 and 2012, found tinnitus in 20.7% of them, and a history of thyroid disease significantly associated with it, alongside other conditions such as hyperlipidemia, osteoarthritis, rheumatoid arthritis, asthma and depression.
A third study looked at thyroid blood tests rather than diagnoses. In 1,165 Korean adults aged 40 and over, a low TSH level — the pattern of an overactive thyroid — carried 2.35-fold higher odds of annoying tinnitus (95% CI 1.10–5.12). The association held even when the thyroid hormone level itself was normal, a state called subclinical hyperthyroidism (2.78-fold, 95% CI 1.21–6.38), and it was apparent in women but not in men. It is a cross-sectional study, so it shows the two occurring together rather than which came first.
Both directions of thyroid dysfunction are implicated
An underactive thyroid shows the same pattern. A second study from Taiwan's national health insurance database followed people diagnosed with hypothyroidism between 2000 and 2010 against a comparison group without it, through to 2011. Tinnitus developed at 9.49 against 6.03 cases per 1,000 person-years, and after adjusting for vertigo, insomnia, anxiety and hearing loss, hypothyroidism carried a 1.35-fold higher risk (95% CI 1.18–1.54). The higher rate held when the groups were split by sex, age, other conditions and length of follow-up.
So the link is not specific to one direction of thyroid dysfunction: an overactive and an underactive thyroid are both associated with more tinnitus, by similar margins. The Korean blood-test study reported its association with the overactive pattern, a low TSH level.
Why the connection might exist
The thyroid gland regulates metabolism throughout the body, including processes relevant to inner ear function and blood flow. Thyroid hormone receptors are present in various tissues beyond the thyroid itself, and dysregulated thyroid hormone levels are thought to potentially affect cochlear blood supply and neural function, though the exact mechanism connecting thyroid dysfunction to tinnitus specifically isn't fully established.
Thyroid disorders also commonly co-occur with anxiety, insomnia, and — in hyperthyroidism particularly — cardiovascular changes that could independently contribute to tinnitus through the mechanisms covered in the articles on tinnitus and anxiety and tinnitus and blood pressure. The Taiwanese study shows how large that overlap is: insomnia was recorded in 45.1% of the hyperthyroidism group against 30.9% of the comparison group, and anxiety in 14.0% against 5.73%. Its adjusted figure accounts for those diagnoses, but it remains hard to fully separate a direct thyroid-to-ear effect from these overlapping pathways.
A detail worth knowing: pulsatile tinnitus specifically
Some clinical sources note that tinnitus associated with hyperthyroidism is more likely to be pulsatile in nature — rising and falling with your heartbeat — plausibly related to the increased cardiac output and blood flow changes that come with an overactive thyroid. If your tinnitus is pulsatile and you have hyperthyroidism, both the thyroid connection and the standard pulsatile tinnitus workup are worth raising with your doctor, since a thyroid explanation does not rule out the other causes of a whooshing sound.
Thyroid eye disease: a treatment with its own ear effects
Thyroid eye disease has a newer treatment that affects the ear directly. Teprotumumab, a monoclonal antibody introduced in 2020, is associated with both tinnitus and hearing loss.
- In a US multi-institutional database study, 947 patients with thyroid eye disease who received teprotumumab were matched with 947 who did not. Over a mean follow-up of just over two years, tinnitus developed in 5.6% against 1.8% (odds ratio 3.13, 95% CI 1.79–5.46), and sensorineural hearing loss in 10.0% against 3.7% (odds ratio 2.89). The authors call for otologic monitoring to avoid possibly irreversible damage.
- In a prospective series of 27 patients, 22 (81.5%) developed new ear symptoms, after an average of 3.8 infusions. At follow-up, around 39 weeks after the last infusion, tinnitus had resolved in every patient who had it, ear fullness in 90.9% and autophony (hearing your own voice too loudly) in 83.3% — but subjective hearing loss had resolved in only 5 of 11. A prior history of hearing loss was a risk factor for the drug-related hearing loss. The authors recommend a hearing test before treatment and repeat testing if new ear symptoms appear.
Ear fullness and autophony are the signature symptoms of a patulous eustachian tube, and one patient in the series developed exactly that. If you are starting teprotumumab, asking about a baseline hearing test is reasonable; if you are on it and notice new tinnitus, fullness or muffled hearing, that is worth reporting promptly rather than waiting for the next scheduled visit.
What treating the thyroid condition tends to do
Case reports and clinical experience suggest that for some patients, tinnitus improves once thyroid hormone levels are brought back into normal range through standard treatment (medication, and in some cases other interventions depending on the specific thyroid condition) — though this isn't universal, and rigorous trial data specifically measuring tinnitus as an outcome of thyroid treatment is limited. This mirrors a pattern seen with other causes: when tinnitus is downstream of an identifiable, treatable condition, addressing that condition directly sometimes resolves the tinnitus, though not reliably enough to guarantee it.