Combination Safety: Benadryl and Metyrosine
Taking Benadryl (diphenhydramine) and Metyrosine together is a combination not typically recommended by doctors. While both medications are approved by the FDA, their interactions require careful consideration.
Benadryl Side Effects and Risks
Benadryl is an antihistamine prescribed to alleviate allergy symptoms and for sedation.[1] Common side effects include drowsiness, dry mouth, and constipation. More severe side effects may include confusion, agitation, and delirium, particularly with high doses.
Metyrosine Mechanism and Interactions
Metyrosine, also known as Demser, is primarily used to treat pheochromocytoma, a rare adrenal gland tumor that causes excessive production of catecholamines.[2] It works by inhibiting the enzyme tyrosine hydroxylase, which is critical for catecholamine production. Metyrosine can cause a range of side effects, including sedation, diarrhea, and dizziness.
Interaction Risks and Contraindications
Combining Benadryl and Metyrosine increases the risk of anticholinergic effects, such as urinary retention, constipation, and dry mouth. Benadryl can exacerbate Metyrosine's sedation and dizziness, potentially increasing the risk of falls or respiratory depression.
Why Doctors May Not Recommend Combining the Medications
In some cases, doctors might consider the combination of Benadryl and Metyrosine for patients with specific conditions. However, the risks of additive side effects and potential interactions often outweigh any potential benefits. Consult your doctor or pharmacist to discuss safe medication options.
Alternatives and Precautions
When choosing an antihistamine, opt for a non-drowsy alternative, such as loratadine (Claritin) or cetirizine (Zyrtec). For patients taking Metyrosine, it is essential to closely monitor for signs of excessive sedation or other adverse effects when co-prescribing another medication.
Pregnancy and Breastfeeding Considerations
Both Benadryl and Metyrosine are usually not recommended during pregnancy or breastfeeding, as the safety of these combinations is not well established.
Sources:
[1] https://www.drugs.com/diphenhydramine.html
[2] https://www.drugs.com/demser-metyrosine.html