<p>Choroquine is well tolerated at the standard dosage regimens, side effects such as headache and gastrointestinal disturbances which may occur are not of a serious nature. Where prolonged high dose is required side effects can be of greater severity and patients may develop skin eruptions, occasional depigmentation or loss of hair, difficulty in accommodation, blurring of vision. Corneal opacities disappear completely when the drug is stopped. Rarely thrombocytopenia, agranulocytosis and aplastic anemia have been reported.<br />
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The most serious toxic hazard of prolonged therapy with doses is the occasional development of irreversible retinal damage. For this reason considerable caution is needed in the use of choroquine for long-term high dosage therapy and such use should only be considered when no other drug is available. Defects in visual accommodation may occur on first taking choloquine and patients should be warned regarding driving or operating machinery.</p>