It's not always clear what causes tinnitus.
It is often linked with:
- some form of hearing loss
- Ménière's disease
- conditions such as diabetes, thyroid disorders or multiple sclerosis
- anxiety or depression
- taking certain medication
Many cases of tinnitus are linked with hearing loss caused by damage to the inner ear. But around 33% of people with the condition don't have any obvious problem with their ears or hearing.
Sounds pass from the outer ear through to the inner ear. The inner ear contains two parts, the cochlea and auditory nerve. Damage to the cochlea is thought to lead to tinnitus.
In older people, damage to the cochlea often happens with age. In younger people, it can be caused by repeated exposure to excessive noise - for example, music concerts.
Tinnitus can be a side effect of:
- some chemotherapy medicines
- non-steroidal anti-inflammatory drugs (NSAIDs)
As well as inner ear damage, there are other possible causes of tinnitus. These include:
- earwax build-up
- middle ear infection
- a build-up of fluid in the middle ear
- a perforated eardrum
- otosclerosis – a condition where abnormal bone growth in the ear causes hearing loss
Less common causes of tinnitus may be:
- a head injury
- sudden or very loud noise, such as an explosion
- acoustic neuroma – a rare non-cancerous growth that affects the hearing nerve
- high blood pressure (hypertension) and narrowing of the arteries (atherosclerosis)
- an overactive thyroid gland (hyperthyroidism)
- underactive thyroid gland (hypothyroidism)
- Paget's disease