<p>Promethazine hydrochloride injection is contraindicated in comatose states and in patients who have demonstrated an idiosyncrasy or hypersensitivity to promethazine or other phenothiazines. Under no circumstances should Promethazine hydrochloride injection be given by intra-arterial injection due to the likelihood of severe arteriospasm and the possibility of resultant&nbsp;gangrene.<br />
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Promethazine hydrochloride injection should not be given by the&nbsp;subcutaneous&nbsp;route; evidence of chemical irritation has been noted, and&nbsp;necrotic&nbsp;lesions have resulted on rare occasions following subcutaneous injection. The preferred parenteral route of administration is by deep&nbsp;intramuscularinjection.</p>