A severe adverse reaction to mefloquine and chloroquine prophylaxis. Permanent hearing disturbances are possible but rare. They are most commonly seen in individuals who take aspirin in large doses for long periods, such as for treatment of arthritis. Mercury and lead are heavy metals which are ototoxic. Practically speaking, these agents are infrequent causes of hearing disturbance.
Noise exposure is the most common source of hearing loss.
Guns and other unilateral sources of noise cause more circumscribed lesions. Noise is often also a co-factor in medication type ototoxicity. Those who have hearing loss from an ototoxic antibiotic, for example, may be at much greater risk from noise. There is some evidence that heavy salt eaters are more susceptable to damage from noise. Little is known about protection.