What is Promethazine DM? Uses, warnings & side effects

How to take Promethazine DM

• Your healthcare provider will advise you on the correct dose and how much medicine to take. Do not use more than directed or prescribed.

• Always follow the instructions from your healthcare provider or those found on the prescription label.

• Measure the oral liquid medicine with a marked measuring spoon, oral syringe, or medicine cup. In many cases, the medication should come with a dose-measuring device. 

• Store at room temperature, away from light or heat.

What to do if you miss a dose of Promethazine DM

• Take a dose as soon as you remember. If it is almost time for your next dose, wait until then and take a regular dose. Do not take extra medicine to make up for a missed dose.

• Ask your pharmacist, doctor, or caregiver about the best way to dispose of any outdated medicine or medicine that is no longer needed.

• Keep all medicine out of the reach of children. Never share your medicine with anyone.

Promethazine DM contraindications - Who shouldn't take Promethazine DM?

• You should not use this medicine if you have ever had an allergic reaction to promethazine, dextromethorphan, or any of their ingredients. 

• You should not use this medicine if you have taken monoamine oxidase inhibitors (MAOIs) such as Nardil (phenelzine), Marplan (isocarboxazid), Eldepryl (selegiline), or Parnate (tranylcypromine) within the past 14 days. 

• This medication is not approved for use in children under two. Using these medicines in very young children may cause serious or possibly life-threatening side effects. 

• Promethazine-DM should not be used in people who are comatose. 

• Promethazine-DM should not be used for the treatment of lower respiratory tract symptoms of conditions like asthma and COPD.

Promethazine DM warnings

• This medicine may contain phenylalanine from the sweetener aspartame. You may need to avoid Promethazine-DM or consider alternatives if you have a disorder called phenylketonuria (a genetic disorder that may lead to brain damage due to an inability to process phenylalanine). 

• If you are pregnant or breastfeeding, talk to your doctor before using this medicine.

• This medicine may make you drowsy. Avoid driving, using machines, or doing anything else that could be dangerous if you are not alert.

• This liquid cough medicine may contain alcohol or sugar.

• Call your doctor if your symptoms get worse after two or three days of treatment, or if they do not improve after 10 to 14 days. You should also contact your healthcare provider if you develop a severe sore throat or fever, as these may be signs of a bacterial infection.

• Children may be more sensitive to this medicine than adults, especially if they take too much medicine. Always read medicine labels carefully and give your child the correct dose. Ask your pharmacist if you are not sure how much medicine to use.

• Make sure your doctor knows if you have other medical conditions, such as heart disease, high blood pressure, diabetes, glaucoma, problems urinating, a seizure disorder, asthma, chronic bronchitis, liver disease, bladder-neck obstruction, sleep apnea, and bone marrow disorders.

Promethazine DM interactions & what to avoid when taking Promethazine DM

Promethazine-DM is linked to several possible drug interactions. These drug interactions may cause serious side effects, especially if the medications are taken in high doses. Examples of potential drug interactions include the following:

• Benzodiazepines: When taken together with Promethazine-DM, benzodiazepines can amplify sedative effects, potentially leading to severe drowsiness and respiratory depression. Caution is advised if these medications are combined.

• Barbiturates: Co-administration with barbiturates may increase the sedative effects of both drugs, increasing the risk of respiratory depression.

• Sedative hypnotics: Combining Promethazine-DM with sedative hypnotics can intensify drowsiness and slow respiratory rates. This can be dangerous and may lead to life-threatening conditions if not monitored.

• Opioids: Opioids, when taken with Promethazine-DM, may cause additive respiratory depressant effects. This raises the risk of respiratory failure, making it important to monitor doses and usage closely.

• Antipsychotic drugs: Combining Promethazine-DM with antipsychotic drugs can cause additive sedative and respiratory depressant effects, which may lead to a dangerous drug interaction, especially at high doses.

• General anesthetics: When taken with general anesthetics, Promethazine-DM can increase the risk of respiratory depression and prolong sedative effects.

• Tricyclic Antidepressants (TCAs): TCAs may increase the sedative effects of Promethazine-DM.

• Epinephrine: Promethazine can block the therapeutic effects of epinephrine, potentially decreasing its effectiveness in treating conditions like anaphylaxis.

• Anticholinergics: Combining Promethazine-DM with anticholinergic drugs can increase the risk of side effects, such as dry mouth, urinary retention, blurred vision, and constipation.

• Monoamine oxidase inhibitors: Taking MAOIs with Promethazine-DM may prolong and intensify anticholinergic and CNS depressant effects.

This is not a complete list of drug interactions. Consult a healthcare provider if you take other medications before starting treatment with Promethazine-DM.