Drug
Promethazine-Phenylephrine
Pronounced
"pro-METH-uh-zeen/fen-ill-EFF-rin"
Drug Interactions
Drug interactions may change how your medications work or increase your risk for serious side effects. This document does not contain all possible drug interactions. Keep a list of all the products you use (including prescription/nonprescription drugs and herbal products) and share it with your doctor and pharmacist. Do not start, stop, or change the dosage of any medicines without your doctor's approval.
Some products that may interact with this drug include: antihistamines applied to the skin (such as diphenhydramine cream, ointment, spray), cabergoline, metoclopramide, pergolide.
Taking MAO inhibitors with this medication may cause a serious (possibly fatal) drug interaction. Avoid taking MAO inhibitors (isocarboxazid, linezolid, metaxalone, methylene blue, moclobemide, phenelzine, procarbazine, rasagiline, safinamide, selegiline, tranylcypromine) during treatment with this medication. Most MAO inhibitors should also not be taken for two weeks before treatment with this medication. Ask your doctor when to start or stop taking this medication.
The risk of serious side effects (such as slow/shallow breathing, severe drowsiness/dizziness) may be increased if this medication is taken with other products that may also cause drowsiness or breathing problems. Tell your doctor or pharmacist if you are taking other products such as opioid pain or cough relievers (such as codeine, hydrocodone), alcohol, marijuana (cannabis), drugs for sleep or anxiety (such as alprazolam, lorazepam, zolpidem), muscle relaxants (such as carisoprodol, cyclobenzaprine), or other antihistamines (such as cetirizine, diphenhydramine).
Check the labels on all your medicines (such as allergy or cough-and-cold products) because they may contain ingredients that cause drowsiness. Ask your pharmacist about using those products safely.
This medication may interfere with certain lab tests (such as some pregnancy tests, blood sugar tests, allergy skin test), possibly causing false test results. Make sure lab personnel and all your doctors know you use this drug.
Negative Interactions
1- Potential Negative Interaction
Promethazine
Henbane
Antihistamines, including promethazine, can cause “anticholinergic” side effects such as dryness of mouth and heart palpitations. Henbane also has anticholinergic activity and side effects. Therefore, use with promethazine could increase the risk of anticholinergic side effects, though apparently no interactions have yet been reported with promethazine and henbane. Henbane should not be taken except by prescription from a physician trained in its use, as it is extremely toxic.
HenbanePromethazine- Blumenthal M, ed. The Complete German Commission E Monographs. Austin, TX: American Botanical Council, 1998, 146.
Explanation Required
1- Needs Explanation
Promethazine-Phenylephrine
Fo-Ti
This interaction is based on this drug belonging to a drug class. While this drug may differ from the text and references below, drugs within this class work in a similar way and this interaction is applicable to drugs within the same class.
Many drugs used in the treatment of high blood pressure cause relaxation or dilation of blood vessels. Laboratory studies show that emodin, a compound in Polygonum multiflorum, also relaxes blood vessels. However, animal studies reveal that phenylephrine blocks the action of emodin. Controlled studies are needed to determine whether Polygonum multiflorum helps people with high blood pressure and whether phenylephrine blocks its beneficial effects.
Fo-TiPromethazine-Phenylephrine- Huang HC, Lee CR, Chao PD, et al. Vasorelaxant effect of emodin, an anthraquinone from a Chinese herb. Eur J Pharmacol 1991;205:289-94.