Promethazine

Medically Reviewed by Dr. Harshi Dhingra, M.D.

Last Reviewed: Aug 04, 2022

Warnings


Promethazine Risks, Warnings, and Complications


Promethazine can cause serious health problems in certain groups of people. Talk to your doctor or pharmacist about other treatment options if you are at high risk of complications from promethazine.

  • SEVERE BREATHING PROBLEMS: Promethazine can cause life-threatening respiratory depression in children younger than 2 years of age, especially if they have health conditions such as sleep apnea or chronic obstructive pulmonary disease or if they are taking other medications that also affect breathing. Adults who have breathing problems, are taking other medications such as certain pain relievers (opioids) or sleeping pills, or are drinking alcohol are also at increased risk.

  • SEVERE TISSUE INJURY: Intravenous promethazine can cause skin irritation and cause the death of skin tissue. This can result in an infection, requiring surgery, or even limb amputation. The risk is higher if promethazine is given through the IV route. This is why instead of intravenous promethazine, the medicine is given intramuscularly (by injection into a muscle). Be vigilant for skin changes if you have received a promethazine injection. Seek immediate medical care if you notice skin darkening, pain, burning, or swelling.

  • EFFECT ON FOCUS AND CONCENTRATION: Taking promethazine can cause severe drowsiness, which can affect your concentration and focus. You should avoid driving a motor vehicle, operating machinery, or doing anything that requires you to be alert until you know how promethazine affects you.

  • SEIZURES: In people who have a history of epilepsy or seizures, taking promethazine can cause more frequent seizures. Give your healthcare professional a complete medical history and tell them if you have seizures or are taking medications to control seizures.

  • UNCONTROLLED BODY MOVEMENTS: In a small number of people, promethazine can cause uncontrolled body movements, such as an abnormal position of the neck, abnormal eye movements, tongue thrusting, and jerky movements of the limbs, or tremors. These are called extrapyramidal symptoms (EPS). The risk of extrapyramidal symptoms with promethazine is higher in older adults (those over age 65) and for those on long-term promethazine treatment. Tell your healthcare provider right away if you notice any unusual body movements while on promethazine.

  • NEUROLEPTIC MALIGNANT SYNDROME: Very rarely, promethazine can cause a condition called neuroleptic malignant syndrome (NMS). This is a potentially life-threatening condition that requires immediate treatment. The risk of neuroleptic malignant syndrome is higher in people who take antipsychotic medications. Give your healthcare provider and pharmacist a complete list of your medications before starting promethazine to avoid any possible drug interactions. Symptoms of NMS may include fever, confusion, muscle stiffness, sweating, and changes in blood pressure and heart rate. Seek immediate medical help if you notice these symptoms.

  • FALL IN WHITE BLOOD CELL LEVELS: Promethazine can lead to a fall in the number of white blood cells in the body. These cells help the body fight infections. Having too few white blood cells can make it harder to fight off infections. This side effect of promethazine is serious and potentially life-threatening. The risk of this occurring is higher in people receiving certain chemotherapy drugs that cause bone marrow depression. If you are taking promethazine regularly, your healthcare provider may ask you to have blood tests done to keep an eye on your white blood cell count.

If you are at high risk of complications from promethazine hydrochloride, your healthcare provider or pharmacist can discuss other treatment options. 

Precautions Before Starting Promethazine

Tell your healthcare professional if you are allergic to promethazine, any other phenothiazines, or any other drugs. 

Give your healthcare provider a complete medical history. Promethazine may not be right for people with certain medical conditions, such as an enlarged prostate, asthma, sleep apnea, chronic obstructive pulmonary disease, glaucoma, seizures, ulcers, cancer, heart disease, or liver disease.

Give your healthcare provider a complete list of medications, including prescription drugs, over-the-counter medicines, vitamins, supplements, and herbal products. This can help avoid serious drug interactions.

If you are an older adult, talk to your doctor about the safety of taking promethazine. There may be other safer treatment options available. 

Tell your doctor if you are pregnant, could be pregnant, are planning a pregnancy, or are breastfeeding.

Precautions During Use of Promethazine

Keep all your appointments with your doctor while on promethazine. Your doctor may want to order blood tests or adjust your dose.

Tell your doctor if you become pregnant while on promethazine. 

Tell your doctors you are taking promethazine before any surgery, including dental procedures.

Promethazine can make you drowsy. Do not drive or operate machinery until you know how this medicine affects you. 

Avoid drinking alcohol while on promethazine, as this can worsen the side effects.

Promethazine can increase sensitivity to sunlight. Use proper sun protection and wear protective clothing while on this drug.

Promethazine Drug Interactions

Taking promethazine with certain other drugs can affect how it works. Interactions between promethazine and other medicines can also increase the risk of severe adverse effects. The following medications can have possible interactions with promethazine: 

  • Mood elevators (antidepressants) like amitriptyline (Elavil), nortriptyline (Aventyl, Pamelor), desipramine (Norpramin), clomipramine (Anafranil), amoxapine (Asendin), imipramine (Tofranil), doxepin (Adapin, Sinequan), trimipramine (Surmontil), and protriptyline (Vivactil)
  • Antihistamines
  • Epinephrine (Epipen)
  • Asthma medications like ipratropium (Atrovent)
  • Barbiturates like phenobarbital (Luminal)
  • Immunosuppressants like azathioprine (Imuran)
  • Cancer chemotherapy
  • Medications used to relieve anxiety, mental illnesses, motion sickness, irritable bowel disease, ulcers, urinary problems, seizures, and Parkinson's disease
  • Narcotics and other medications used for pain relief
  • Sedatives, tranquilizers, and sleeping pills 
  • Monoamine oxidase (MAO) inhibitors such as phenelzine (Nardil), isocarboxazid (Marplan), selegiline (Eldepryl, Emsam, Zelapar), and tranylcypromine (Parnate)

The above list may not describe all possible promethazine interactions. Give your doctor and pharmacist a list of all your current medications, including prescription drugs, over-the-counter medications, dietary supplements, and herbal remedies. Also, tell your health care provider if you smoke, drink alcohol, or use recreational drugs because some of these substances can cause serious health complications when used with prescription medicines.