Promethazine Side Effects
Insomnia, dry mouth, and fatigue are some of the more common side effects of promethazine that people may experience. These problems are generally mild and either do not require treatment or can be treated easily. However, certain side effects are potentially serious and require prompt medical attention, such as high fever, hyperactivity, or irregular breathing.
As with any medicine, side effects are possible with promethazine hydrochloride (Phenergan®). However, not everyone who takes the medication will have 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.
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.
(This article covers many, but not all, of the possible side effects with promethazine. Your healthcare provider can discuss a more complete list of promethazine side effects with you.)
Some promethazine side effects are serious -- even life-threatening -- and should be reported to your healthcare provider. These include, but are not limited to:
- Slow or irregular breathing
- High blood pressure (hypertension) or low blood pressure (hypotension)
- A rapid heart rate (tachycardia) or slow heart rate (bradycardia)
- Signs or symptoms of neuroleptic malignant syndrome, which can include:
- A high fever
- Stiff muscles
- Irregular pulse or blood pressure
- An increased heart rate (tachycardia)
- Irregular heart rhythms (arrhythmias)
- Involuntary muscle movements
Frequent infections or easy bruising or bleeding, which may be signs of blood cell problems
- Yellow skin (jaundice)
- A protruding tongue
- Strange eye movements or positioning
- Signs of an allergic reaction, such as:
- An unexplained rash
- Unexplained swelling (especially of the lips, mouth, or throat)
- Wheezing or other breathing problems.
If you are receiving promethazine through an IV, tell your doctor if you experience severe pain, as this may be a sign that the drug was administered incorrectly or is leaking from the vein into surrounding tissue. This can cause permanent tissue damage, including gangrene. Some cases have resulted in amputation. Seek medical attention if this occurs, and make sure your concerns are taken seriously.