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Benadryl Patient Tips

Written by C. Fookes, BPharm on Oct 21, 2016

How it works

Benadryl is a brand (trade) name for diphenhydramine. Diphenhydramine is an antihistamine that works on histamine receptors to block the allergic response.


  • Used to treat allergic-type reactions including allergic conjunctivitis, urticaria (hives), and in addition to epinephrine for an anaphylactic reaction.
  • Also effective at relieving motion sickness.
  • Good for controlling symptoms such as sneezing, itching, watery eyes, and runny nose.
  • May also be used for elderly people with Parkinson's disease unable to tolerate more potent agents.
  • Can be used as a night-time sleep aid.


If you are between the ages of 18 and 60, take no other medication or have no other medical conditions, side effects you are more likely to experience include:

  • Dizziness, low blood pressure, a dry mouth, headache, abdominal discomfort, rapid heart beat, disturbed coordination, and a thickening of bronchial secretions.
  • Benadryl may cause drowsiness and sedation and affect your ability to drive or operate machinery. Avoid alcohol.

Notes: In general, seniors or children, people with certain medical conditions (such as liver or kidney problems, heart disease, diabetes, seizures) or people who take other medications are more at risk of developing a wider range of side effects. For a complete list of all side effects, click here.

Bottom Line

Benadryl is an antihistamine that can be used to treat allergic reactions, relieve motion sickness, and as a sleep aid; however, it is likely to cause drowsiness.


  • Do not drive or operate machinery if Benadryl makes you drowsy or affects your judgment. Avoid alcohol.
  • When using for motion sickness, take Benadryl 30 minutes before exposure to motion. Take subsequent doses before meals or bedtime for the duration of the exposure.
  • Not recommended as a night-time sleep aid for children aged less than twelve.

Response and Effectiveness

Benadry is quickly absorbed with maximum activity occurring within one hour. Effects of Benadryl last from four to six hours.


Benadryl [Package Insert] Revised 05/2006. Parke-Davis.

  • Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use Benadryl only for the indication prescribed.

  • Disclaimer: Every effort has been made to ensure that this information is accurate, up-to-date, and complete, but no guarantee is made to that effect. Drug information contained herein may be time sensitive. This drug information does not endorse drugs, diagnose patients or recommend therapy. It is an informational resource designed as a supplement to, and not a substitute for, the expertise, skill, knowledge and judgment of healthcare practitioners. The absence of a warning for a given drug or drug combination in no way should be construed to indicate that the drug or drug combination is safe, effective or appropriate for any given patient. does not assume any responsibility for any aspect of healthcare administered with the aid of this information. 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.

Copyright 1996-2017 Revision Date: 2016-10-21 00:00:00