The major hazards of meperidine, as with other narcotic analgesics, are respiratory depression and, to a lesser degree, circulatory depression; respiratory arrest, shock, and cardiac arrest have occurred.

The most frequently observed adverse reactions include light-headedness, dizziness, sedation, nausea, vomiting, and sweating. These effects seem to be more prominent in ambulatory patients and in those who are not experiencing severe pain. In such individuals, lower doses are advisable. Some adverse reactions in ambulatory patients may be alleviated if the patient lies down.

Other adverse reactions include:

CENTRAL NERVOUS SYSTEM

Euphoria, dysphoria, weakness, headache, agitation, tremor, uncoordinated muscle movements, transient hallucinations and disorientation, visual disturbances and, rarely, extrapyramidal reactions.

GASTROINTESTINAL

Dry mouth, constipation, biliary-tract spasm.

CARDIOVASCULAR

Flushing of the face, tachycardia, bradycardia, palpitation, faintness, syncope.

Cardiovascular effects from promethazine have been rare. Minor increases in blood pressure and occasional mild hypotension have been reported. Venous thrombosis at the injection site has been reported. Intra-arterial injection of Mepergan (meperidine and promethazine) may result in gangrene of the affected extremity (see " WARNINGS").

GENITOURINARY

Urinary retention.

ALLERGIC

Pruritus, urticaria, other skin rashes, wheal and flare over the vein with IV injection.

Photosensitivity, although extremely rare, has been reported. Occurrence of photosensitivity may be a contraindication to further treatment with promethazine or related drugs.

OTHER

Pain at injection site; local tissue irritation, induration, and possible tissue necrosis, particularly when injection is repeated at same site; antidiuretic effect.

Patients may occasionally complain of autonomic reactions, such as dryness of the mouth, blurring of vision and, rarely, dizziness following the use of promethazine.

Very rare cases have been reported where patients receiving promethazine have developed leukopenia. In one instance agranulocytosis has been reported. In nearly every instance reported, other toxic agents known to have caused these conditions have been associated with the administration of promethazine.

Read the Mepergan (meperidine and promethazine) Side Effects Center for a complete guide to possible side effects »

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Last reviewed on RxList: 12/8/2004
This monograph has been modified to include the generic and brand name in many instances.