Quinidine side effects

Quinidine preparations have been used for many years, but there are only sparse data from which to estimate the incidence of various adverse reactions. The adverse reactions most frequently reported have consistently been gastrointestinal, including diarrhea, nausea, vomiting, and heart–burn/esophagitis.

List of Side Effects
Muscle pain Vomiting and diarrhea Hepatotoxicity Autoimmune and inflammatory syndromes Convulsions, apprehension, and ataxia Other adverse reactions

Muscle pain
Intramuscular injections of Quinidine gluconate are typically followed by moderate to severe local pain. Some patients will develop tender nodules at the site of injection that persist for several weeks. Return to top

Vomiting and diarrhea
Vomiting and diarrhea can occur as isolated reactions to therapeutic levels of Quinidine, but they may also be the first signs of cinchonism, a syndrome that may also include tinnitus, reversible high–frequency hearing loss, deafness, vertigo, blurred vision, diplopia, photophobia, headache, confusion, and delirium. Cinchonism is most often a sign of chronic Quinidine toxicity, but it may appear in sensitive patients after a single moderate dose. Return to top

Hepatotoxicity
A few cases of hepatotoxicity, including granulomatous hepatitis, have been reported in patients receiving Quinidine. All of these have appeared during the first few weeks of therapy, and most (not all) have remitted once Quinidine was withdrawn. Return to top

Autoimmune and inflammatory syndromes
Autoimmune and inflammatory syndromes associated with Quinidine therapy have included fever, urticaria, flushing, exfoliative rash, bronchospasm, pneumonitis, psoriasiform rash, pruritus and lymphadenopathy, hemolytic anemia, vasculitis, thrombocytopenic purpura, uveitis, angioedema, agranulocytosis, the sicca syndrome, arthralgia, myalgia, elevation in serum levels of skeletal–muscle enzymes, and a disorder resembling systemic lupus erythematosus. Return to top

Convulsions, apprehension, and ataxia
Convulsions, apprehension, and ataxia have been reported, but it was not clear that these were not simply the results of hypotension and consequent cerebral hypoperfusion. There are many reports of syncope. Acute psychotic reactions have been reported to follow the first dose of Quinidine, but these reactions appear to be extremely rare. Return to top

Other adverse reactions
Other adverse reactions occasionally reported include depression, mydriasis, disturbed color perception, night blindness, scotomata, optic neuritis, visual field loss, photo–sensitivity, and abnormalities of pigmentation. Return to top