Interventions for Tuberculosis Control and Elimination 2002

Table 5. Summary of adverse reactions from ethambutol with estimated frequencies
of occurrence. Note that these are estimates of frequencies, which may
vary across population groups.
Frequent Common Infrequent Rare
(� 5 per 100) (� 1 per 100 and (� 1 per 1,000 (< 1 per 1,000)
< 5 per 100) and < 1 per 100)
Retrobulbar Aplastic anemia
neuritis Eosinophilic pneumonia
Periaxial ocular Thrompocytopenia
toxicity Hyperuricemia
and loss of ability to see green (reported as white or gray). The ability to
see red, which has been reported as pink, has occasionally been affected.
Those with periaxal toxicity have a defect in the peripheral isopters of their
field of vision, with little or no decrease in visual acuity and normal redgreen
color discrimination. The optic discs and the fundi appeared normal
in both types of toxicity. The incidence of ocular toxicity is dose dependent.
372,379 The chance of visual recovery appears to be related to the total
dose administered and the initial degree of loss of vision. 370 It has been
recommended not to use ethambutol in children too young for objective
tests for visual acuity. 363 There is, however, no evidence that children are
particularly prone to ocular toxicity, 380 and ethambutol may thus be used
in children. However, as children might be less likely to report ocular toxicity,
particular caution may be warranted. Ocular toxicity is usually
reversible upon cessation of ethambutol administration, but recovery might
be protracted. 368 Compared to the frequency of fatal outcome resulting
from anti-tuberculosis medication, the occurrence of blindness from ethambutol
is rare. 367
Ethambutol may cause aplastic anemia, 367 but this is exceedingly rare.
Ethambutol is a rare cause of pulmonary infiltrates with eosinophilia, 381
rash, 367,382 exacerbation of lupus erythematosus, 330 thrombocytopenia 383 and
hyperuricemia. 384
Interactions
Effect of ethambutol potentiated: Although listed in some text books, ethionamide
and isoniazid have not been conclusively shown to increase ethambutol
ocular toxicity.
Effect of ethambutol opposed: Aluminum-magnesium antacid reduces
ethambutol resorption, and lowers and delays, respectively, C max and T max . 355
40