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Discontinued Warning IconPlease Note: This Brand Name drug is no longer available in the US.
(Generic versions may still be available.)

Mepergan Side Effects Center

Medical Editor: John P. Cunha, DO, FACOEP

Last reviewed on RxList 11/20/2015

Mepergan (meperidine and promethazine) is a narcotic pain reliever used as a pre-anesthetic medication when analgesia and sedation are indicated, and as an adjunct to local and general anesthesia. The brand name Mepergan is discontinued, but generic versions may be available. Common side effects of Mepergan (meperidine and promethazine) include lightheadedness, dizziness, drowsiness, sedation, nausea, vomiting, sweating, flushing of the face and neck, weakness, constipation, nervousness, excitability, ringing in the ears, and sensitivity of skin to sunlight.

The adult dose of Mepergan is 1 to 2 mL (25 to 50 mg of each component) per single injection, which can be repeated every 3 to 4 hours. Mepergan may interact with other narcotics, general anesthetics, phenothiazines, other tranquilizers, sedative-hypnotics, antidepressants, and other CNS depressants (including alcohol). Tell your doctor all medications and supplements you use. Mepergan should not be used during pregnancy. Tell your doctor if you are pregnant or plan to become pregnant before using Mepergan. This drug passes into breast milk. Consult your doctor before breastfeeding. Withdrawal symptoms may occur if you suddenly stop taking this medication.

Our Brand name (generic) Side Effects Drug Center provides a comprehensive view of available drug information on the potential side effects when taking this medication.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

What is Prescribing information?

The FDA package insert formatted in easy-to-find categories for health professionals and clinicians.

Mepergan FDA Prescribing Information: Side Effects
(Adverse Reactions)


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:


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


Dry mouth, constipation, biliary-tract spasm.


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").


Urinary retention.


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.


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 entire FDA prescribing information for Mepergan (Meperidine and Promethazine)

Report Problems to the Food and Drug Administration


You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.

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