by Dr. Manura Nanayakkara

Created on: October 26, 2010

This is the popular brand name of the prescription drug Promethazine. It is a first generation anti histamine with some nasty side effects. It is used mainly to treat vomiting, allergic reactions, motion sickness and to induce sleep. In addition this medication is available as tablets as well as syrup form for children. Side effects are more severe in elderly patients.

How Phenergan works?

This drug acts by blocking histamine (H1) receptors in the body. In addition it crosses the blood brain barrier, so sedation and drowsiness are common side effects. But drowsiness can be tolerable over time. 

If you have

* Kidney diseases

* Liver diseases

* Urine block or enlarged prostate gland

* Glaucoma

 * Epilepsy

* Sleep apnea or making sounds when you are asleep

Then you should not take this medication without a doctor’s advice. You should not take this if you are pregnant or nursing unless prescribed by a doctor. This drug should not be used by nursing mothers.

What are the common side effects?

Drowsiness is the commonest side effect of Phenergan. Headache, urinary retention, and blurred vision are also common side effects. Naso pharyngitis, fatigue and dry mouth are common side effects as well. If you are taking Phenergan, then it is important to avoid operating machinery, driving motor vehicles, and taking excess alcohol or any taking any other CNS depressant drugs.

In addition this drug is known to cause listlessness. Some patients can dizzy with this medication. Frequent nightmares will increase with this drug. Loss of muscle coordination is another problem. Some people may get an abnormal happy mood.

How can you avoid certain side effects?

Take this medication only in recommended dosage without exceeding the dose. This medication should be taken with a full glass of water. Do not crush the medication before use. Do not eat high fat meal at the time of taking the drug. High fat meals decreases blood concentration of above medication.

What are the side effects that are not so common?

Somnolence, fatigue, and reduced energy are reported. Sometimes patients can get low blood pressure, increased heart rate and cardiac rhythm abnormalities. Sleep disturbance is another troublesome side effect that can occur. Very rarely patients can get tremors and convulsions (fits).

Rare side effects that are specific to Phenergan are exforliative dermatitis (skin peeling off), tinnitus, short term blood pressure reduction, and abnormal Central nervous system stimulation.

Summary

Phenergon is a common prescrition only anti histamine used for many conditions. But it has some nasty side effects. So always get medical advice before taking this drug.

AHFS Drug Information

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