Name: Benadryl

Benadryl Overview

Benadryl is an over the counter medication used to treat the symptoms of seasonal allergies and hay fever. Benadryl can also be used for trouble sleeping, motion sickness, coughing, and Parkinsonism. Benadryl belongs to a group of drugs called Histamine H1 Antagonists (antihistamine). Antihistamines work by blocking the action of histamine, which is known to trigger allergy symptoms. 

This medication comes in a tablet, capsule and oral (by mouth) solution and is taken every 4 to 8 hours as needed, with or without food. 

Common side effects of Benadryl include confusion, dry mouth, and blurry vision. Benadryl can also cause drowsiness. Do not drive or operate heavy machinery until you know how Benadryl affects you. 

Commonly used brand name(s)

In the U.S.

  • Ala-Hist AC
  • Ala-Hist DHC
  • Alavert-D 12-Hour
  • Aldex D
  • Alka-Seltzer Plus Cold and Sinus
  • AllanVan-S
  • Allegra-D
  • Aller-Chlor
  • Allerx-D
  • Allfen CD
  • Allres PD
  • Amibid LA
  • Benadryl
  • BPM Pseudo
  • Bromcomp HC
  • Bromfed-PD
  • BroveX CB
  • By-Ache
  • Canges-HC
  • Ceron
  • Ceron-DM
  • Chlor-Trimeton Nasal Decongestant
  • Clarinex-D
  • Codimal DH
  • Cotab A
  • Cotabflu
  • Cypex-LA
  • Deconamine SR
  • Delsym
  • Dexphen w/C
  • Donatussin DC
  • Donnatussin
  • D-Tann HC
  • EndaCof-DC
  • FluTuss XP
  • Genapap Sinus
  • G Phen DM
  • HC Tussive
  • Histex PD
  • Humibid DM
  • Hycodan
  • Hycofenix
  • Hydone
  • HyTan
  • Kie
  • Levall 12
  • Lusonal
  • Maxiflu CD
  • Maxiphen CD
  • M-End Max D
  • Mucinex D
  • Nasop
  • Notuss-Forte
  • Notuss-NX
  • Notuss-NXD
  • Novahistine DH
  • Pancof HC
  • Pediatex 12
  • Pediatex 12D
  • Pediatex 12DM
  • Pediatex-D
  • Phenergan w/Codeine
  • Phenflu CD
  • Phenylephrine CM
  • Phenylhistine
  • Poly-Tussin AC
  • Poly-Tussin DHC
  • Pro-Clear AC
  • Promethazine VC With Codeine
  • Pro-Red AC
  • RelaTuss HC
  • Robitussin
  • Robitussin DM
  • Ryneze
  • Semprex-D
  • SSKI
  • Stahist
  • Sudafed
  • SymTan
  • SymTan A
  • Tanafed DMX
  • Tannate Pediatric
  • Tessalon Perles
  • Tricold Pediatric Drops
  • Tripohist D
  • Tussi-12 S
  • TussiCaps
  • Tuzistra XR
  • Tylenol
  • Uni-Tann D
  • Vituz
  • Xpect-PE
  • Y-Cof DM
  • Z-COF DM
  • Zhist
  • Zodryl DAC 25
  • Zotex-D
  • Zymine
  • Zymine HC
  • ZyrTEC-D

In Canada

  • Actifed A
  • Actifed Plus
  • Actifed Plus Extra Strength
  • Actifed Plus Head Cold And Sinus Extra Strength
  • Actifed Sinus Regular
  • Adult Nighttime Cold/Flu Relief - Cherry Flavor
  • Adult Nighttime Cold/Flu Relief - Original Flavor
  • Allergy Sinus Medication Extra Strength
  • Atoma Night Adult Cold/Flu Relief
  • Balminil
  • Balminil Dm Children
  • Balminil Dm Sugar-Free

Available Dosage Forms:

  • Suspension
  • Tablet, Disintegrating
  • Tablet, Chewable
  • Solution
  • Tablet
  • Syrup
  • Suspension, Extended Release
  • Tablet, Extended Release
  • Elixir
  • Liquid
  • Capsule, Extended Release
  • Capsule
  • Capsule, Liquid Filled
  • Capsule, Extended Release, 12 HR
  • Packet
  • Tablet, Extended Release, 12 HR
  • Film
  • Tablet, Effervescent
  • Powder for Suspension
  • Powder for Solution
  • Kit
  • Tablet, Extended Release, 24 HR
  • Capsule, Extended Release, 24 HR
  • Tablet, Enteric Coated

Uses of Benadryl

  • It is used to ease allergy signs.
  • It is used to help motion sickness.
  • It is used to treat signs like Parkinson's disease caused by other health problems.

How is this medicine (Benadryl) best taken?

Use this medicine as ordered by your doctor. Read all information given to you. Follow all instructions closely.

  • It is given as a shot into a muscle or vein.
  • This medicine may cause tissue damage if it is given into the skin or into the fatty part under the skin. Talk with the doctor.

What do I do if I miss a dose?

  • Call your doctor to find out what to do.

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.

What other drugs will affect diphenhydramine?

Ask a doctor or pharmacist before using this medicine if you are also using any other drugs, including prescription and over-the-counter medicines, vitamins, and herbal products. Some medicines can cause unwanted or dangerous effects when used together. Not all possible interactions are listed in this medication guide.

Taking this medicine with other drugs that make you sleepy or slow your breathing can worsen these effects. Ask your doctor before taking diphenhydramine with a sleeping pill, narcotic pain medicine, muscle relaxer, or medicine for anxiety, depression, or seizures.