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Drug Interactions between Benadryl and Spiriva

This report displays the potential drug interactions for the following 2 drugs:

  • Benadryl (diphenhydramine)
  • Spiriva (tiotropium)

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Interactions between your drugs


diphenhydrAMINE tiotropium

Applies to: Benadryl (diphenhydramine) and Spiriva (tiotropium)

Using diphenhydrAMINE together with tiotropium may increase side effects such as drowsiness, blurred vision, dry mouth, heat intolerance, flushing, decreased sweating, difficulty urinating, abdominal cramping, constipation, rapid heart beat, confusion, memory problems, and glaucoma. Although serious side effects are not very common with inhaled or topically applied preparations because only limited amounts of the medication generally get absorbed into the bloodstream from the lungs or skin, they can sometimes occur, especially in the elderly or when combined with other medications that have similar side effects. Talk to your doctor if you have any questions or concerns. Your doctor may be able to prescribe alternatives that do not interact. You should avoid activities requiring mental alertness such as driving or operating hazardous machinery until you know how these medications affect you. When using an inhaled product by nebulizer, keep your eyes closed or use an eye mask to avoid having the medication get into the eyes, which can cause blurry vision and eye pain as well as increase absorption of the medication into the bloodstream. When using a topical preparation such as a cream or solution, avoid applying to broken skin or using occlusive dressings over the application areas, and also avoid touching the eyes until after you wash your hands with soap and water. It is important to tell your doctor about all other medications you use, including vitamins and herbs. Do not stop using any medications without first talking to your doctor.

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Drug and food interactions

No interactions were found. This does not necessarily mean no interactions exist. Always consult your healthcare provider.

Therapeutic duplication warnings

No warnings were found for your selected drugs.

Therapeutic duplication warnings are only returned when drugs within the same group exceed the recommended therapeutic duplication maximum.

Drug Interaction Classification

These classifications are only a guideline. The relevance of a particular drug interaction to a specific individual is difficult to determine. Always consult your healthcare provider before starting or stopping any medication.
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 interaction information available.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.