isoniazid (Nydrazid, Laniazid, INH are all discontinued brands) (cont.)

Pharmacy Author:
Medical and Pharmacy Editor:

The risk of developing hepatitis is age-related. It occurs in less than 1 per 1,000 patients under 20 years of age, 3 per 1,000 patients 20-34 years of age, 12 per 1,000 patients 35-49 years of age, 23 per 1,000 patients 50-64 years of age, and 8 per 1,000 patients over 65 years of age. The risk of hepatitis is increased by daily consumption of alcohol. Among individuals who complete a full course of prophylaxis (prevention of tuberculosis), the hepatitis-related death rate (mortality) is 23-58 patients per 100,000 patients, far lower than the frequency of hepatitis. The mortality rate among individuals who develop symptoms of Isoniazid-induced hepatitis (not just minor abnormalities of liver tests) is approximately 10%. In one U. S. Public Health Service Surveillance Study involving 13,838 persons taking Isoniazid, there were 8 deaths among 174 cases of hepatitis, a mortality rate of 5%.

There seems to be an increased risk of fatal hepatitis among women, particularly African-American and Hispanic women. The risk also may be increased during postpartum or immediately after pregnancy. Because of the risk of hepatitis, patients taking isoniazid should have their blood liver tests monitored monthly and should notify their physicians immediately if symptoms or signs of hepatitis arise. These symptoms and signs include:

Damage to nerves (peripheral neuropathy) may occur with isoniazid and cause numbness and tingling of the hands or feet.

Other rare side effects of the nervous system include:

  • encephalopathy (inflammation of the brain),
  • optic neuritis (inflammation of the nerve coming from the eye),
  • atrophy (degeneration) of the nerve coming from the eye,
  • seizures,
  • impaired memory,
  • psychosis.
Medically Reviewed by a Doctor on 2/11/2015


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