Promethazine hydrochloride (
Phenergan®) is a prescription medication approved for a variety of widely different uses. It is probably used most often as a nausea medication, although it is frequently used for other purposes as well.
It should be noted that this article applies only to products that contain just promethazine as the active ingredient. Some promethazine cough syrups (such as Phenergan with Codeine) contain other active ingredients as well.
Just like any medicine, promethazine may cause side effects. However, not everyone who takes the drug will experience problems. In fact, most people tolerate it quite well. If side effects do occur, in most cases, they are minor and either require no treatment or can easily be treated by you or your healthcare provider. Serious reactions are less common.
Some of the side effects seen with promethazine include, but are not limited to:
- Drowsiness
- Confusion
- Dry mouth.
(Click Promethazine Side Effects to learn more, including potentially serious side effects you should report immediately to your healthcare provider.)
What Should I Tell My Healthcare Provider?
You should talk with your healthcare provider prior to taking promethazine if you have:
Also, let your healthcare provider know if you are:
Make sure to tell your healthcare provider about all other medicines you are taking, including prescription and nonprescription medicines, vitamins, and herbal supplements.
How Does Promethazine Work?
Promethazine has several different effects in the body and the brain. Many of these effects are likely due to its antihistamine activity, since the drug works by blocking histamine receptors.
Promethazine also belongs to a group of medications known as phenothiazines. Although phenothiazines are usually used as
antipsychotic medications, promethazine has little dopamine-blocking activity. This makes it a weak antipsychotic medication, and it is not used for this purpose.
This medicine also blocks acetylcholine receptors, which is probably why it helps to alleviate nausea and motion sickness.
When and How to Take This Medication
Some general considerations for those taking promethazine include the following:
- Promethazine comes in tablet, rectal suppository, syrup, and injectable form. It is usually taken one to three times daily.
- You can take this medicine with or without food.
- Great care should be taken if promethazine is injected intravenously, as improper administration can cause severe tissue damage, including gangrene. In some cases, amputations have resulted.
Promethazine should not be given by "IV push" (when the medication is injected with a syringe rapidly into the IV line rather than dripped slowly into it). Injection directly into a muscle is the preferred way to inject this drug in most situations.
- For the medication to work properly, it must be taken as prescribed.
The dose of promethazine your healthcare provider recommends will vary, depending on a number of factors, including:
- The medical condition being treated
- Your age and weight (for children)
- Other medications you may be taking
- Other medical conditions you may have.
As always, do not adjust your dose unless your healthcare provider specifically instructs you to do so.
People who take too much of this medication may experience effects such as (but not limited to):
- Extreme drowsiness
- Low blood pressure
- Decreased breathing
- Unconsciousness
- Overactive reflexes and muscle tone
- Sudden death.
If you happen to overdose on promethazine, seek medical attention right away.
What Should I Do If I Miss a Dose of Promethazine?
If you forget to take a dose of this medication, take it as soon as possible. However, if it is almost time for your next dose, simply skip the one you missed and continue with your regular schedule. Do not take a double dose of promethazine.
You should store both tablets and syrup at room temperature, away from light and moisture. The suppositories should be kept in the refrigerator. Keep promethazine and all other medications out of the reach of children and pets.
Is There a Generic Version?
This medication is available in generic form. In fact, brand-name
promethazine tablets, syrup, and suppositories are no longer available.
Brand-name promethazine tablets, syrup, and suppositories were made by Wyeth Pharmaceuticals, Inc. but are no longer available. The brand-name injectable form is made by Baxter Healthcare Corporation. Generic versions are made by various manufacturers.
The medication is available in the following strengths and forms:
- Promethazine 12.5 mg tablets and rectal suppositories
- Promethazine 25 mg tablets and rectal suppositories
- Promethazine 50 mg tablets and rectal suppositories
- Promethazine 6.25 mg per 5 mL syrup
- Promethazine 25 mg per mL injection vials and ampuls (1 mL)
- Promethazine 50 mg per mL injection vials and ampuls (1 mL).
