Skip to Content

Pseudoephedrine / terfenadine and Alcohol / Food Interactions

There is 1 alcohol/food/lifestyle interaction with pseudoephedrine / terfenadine:


terfenadine ↔ food

Major Food Interaction

Consumer information for this interaction is not currently available.

CONTRAINDICATED: The consumption of grapefruit juice has been associated with significantly increased plasma concentrations of terfenadine. The mechanism is inhibition of CYP450 3A4-mediated first-pass metabolism in the gut wall induced by certain compounds present in grapefruits. Terfenadine in high serum levels has been associated with prolongation of the QT interval and development of torsade de pointes, a potentially fatal ventricular arrhythmia.

MANAGEMENT: Due to the risk of cardiotoxicity, patients receiving the drug should be advised to avoid consumption of grapefruit products. Loratadine, cetirizine, and fexofenadine may be safer alternatives in patients who may have trouble adhering to the dietary restriction.


  1. Zimmermann M, Duruz H, Guinand O, et al "Torsades de Pointes after treatment with terfenadine and ketoconazole." Eur Heart J 13 (1992): 1002-3
  2. Honig PK, Wortham DC, Zamani K, et al "Terfenadine-ketoconazole interaction: pharmacokinetic and electrocardiographic consequences." JAMA 269 (1993): 1513-8
  3. Pohjola-Sintonen S, Viitasalo M, Toivonene L, Neuvonen P "Torsades de pointes after terfenadine-itraconazole interaction." BMJ 306 (1993): 186
View all 17 references

pseudoephedrine / terfenadine drug Interactions

There are 561 drug interactions with pseudoephedrine / terfenadine

pseudoephedrine / terfenadine disease Interactions

There are 6 disease interactions with pseudoephedrine / terfenadine which include:

Drug Interaction Classification

The classifications below are a general guideline only. It is difficult to determine the relevance of a particular drug interaction to any individual given the large number of variables.
Major Highly clinically significant. Avoid combinations; the risk of the interaction outweighs the benefit.
Moderate Moderately clinically significant. Usually avoid combinations; use it only under special circumstances.
Minor Minimally clinically significant. Minimize risk; assess risk and consider an alternative drug, take steps to circumvent the interaction risk and/or institute a monitoring plan.
Unknown No information available.

Do not stop taking any medications without consulting your healthcare provider.

Disclaimer: Every effort has been made to ensure that the information provided by Multum is accurate, up-to-date and complete, but no guarantee is made to that effect. In addition, the drug information contained herein may be time sensitive and should not be utilized as a reference resource beyond the date hereof. This material does not endorse drugs, diagnose patients, or recommend therapy. Multum's information is a reference resource designed as supplement to, and not a substitute for, the expertise, skill, knowledge, and judgement of healthcare practitioners in patient care. The absence of a warning for a given drug or combination thereof in no way should be construed to indicate that the drug or combination is safe, effective, or appropriate for any given patient. Multum Information Services, Inc. does not assume any responsibility for any aspect of healthcare administered with the aid of information Multum provides. Copyright 2000-2017 Multum Information Services, Inc. The information contained herein is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. If you have questions about the drugs you are taking, check with your doctor, nurse, or pharmacist.