Benadryl (diphenhydramine) and Singulair (montelukast) are medications used for allergy symptoms and related conditions. Benadryl, available over-the-counter, is a well-known antihistamine, while Singulair is a prescription medication often used for asthma and allergies. This article clarifies if these medications can be safely taken together, examining their functions and co-administration considerations.
Understanding Benadryl and Singulair
Benadryl functions as a first-generation H1 blocker antihistamine. It primarily works by blocking histamine H1 receptors, which helps reduce symptoms such as sneezing, itching, watery eyes, and runny nose. Diphenhydramine also has anticholinergic effects and can cross the blood-brain barrier, contributing to its notable side effect of drowsiness and its use as a sleep aid. Benadryl is used for allergy symptoms, cold symptoms, mild insomnia, and motion sickness.
Singulair is a leukotriene receptor antagonist. When allergens are inhaled, the body releases chemicals called leukotrienes, which cause inflammation in the lungs and tightening of airway muscles. Montelukast works by blocking the effects of these leukotrienes, reducing inflammation and constriction in the airways. It is prescribed to prevent asthma attacks, manage exercise-induced bronchoconstriction, and treat symptoms of allergic rhinitis, including seasonal and perennial allergies. Singulair is not a rescue medication for acute asthma attacks.
Co-Administration Considerations
Combining Benadryl and Singulair typically does not cause a direct drug interaction. Singulair is typically considered non-drowsy. However, the primary concern when taking these medications together is the potential for additive side effects, particularly increased central nervous system (CNS) depression.
Benadryl is well-known for causing drowsiness, dizziness, and impaired coordination due to its sedative properties. Although Singulair does not typically cause these sedative effects, the combination can amplify the drowsiness and cognitive impairment caused by Benadryl, affecting alertness and motor skills.
Managing Potential Side Effects and Precautions
Benadryl’s common side effects include drowsiness, dizziness, dry mouth, blurred vision, and constipation. Singulair’s potential side effects include headache, stomach upset, and respiratory infections. More significantly, Singulair carries a boxed warning from the FDA regarding potential neuropsychiatric effects, including mood changes, agitation, aggression, anxiety, depression, sleep disturbances, and even suicidal thoughts and behaviors.
The combined use of Benadryl and Singulair heightens the risk of central nervous system depression, leading to increased drowsiness, difficulty concentrating, and impaired motor skills. To mitigate these risks, individuals should avoid driving or operating heavy machinery until they understand how the combination affects them. It is also advisable to avoid alcohol or other sedatives, as these can further intensify drowsiness and other CNS depressant effects. Starting with the lowest effective dose of Benadryl can help assess individual tolerance.
Elderly individuals may be more sensitive to Benadryl’s sedative effects, increasing their risk of dizziness and falls. Children can also experience side effects such as excitability or hyperactivity from Benadryl, and it should not be used to make a child sleepy. Individuals with pre-existing conditions like glaucoma, prostate enlargement, or certain heart conditions should use caution, as Benadryl can worsen these issues.
When to Consult a Healthcare Professional
Consult a doctor or pharmacist before combining any medications, especially with pre-existing conditions like heart disease, liver or kidney issues, or respiratory conditions such as asthma or COPD. A healthcare provider can assess your health profile and current medications to determine potential interactions and suitability.
Seek medical attention if you experience severe or unusual side effects, such as extreme drowsiness, confusion, difficulty breathing, or signs of an allergic reaction like hives or swelling. If symptoms do not improve or worsen, further medical evaluation is warranted. Consultation is also advised for specific situations, including pregnancy, breastfeeding, or if you are taking other prescription or over-the-counter medications that might interact with Benadryl or Singulair.