Benadryl dosage, forms, and strengths

Benadryl (diphenhydramine) is an over-the-counter medication that temporarily relieves allergy symptoms caused by a natural substance in the body called histamine. Diphenhydramine, the active ingredient in brand-name Benadryl, is an antihistamine that blocks the activity of histamine to reduce symptoms such as runny nose, watery eyes, and itching. 

Diphenhydramine also causes drowsiness and slows down the part of the brain that controls nausea. For these reasons, Benadryl can also be used to provide occasional insomnia relief or prevent motion sickness. 

For patients older than 12, the standard dosage of Benadryl Allergy is 25 to 50 mg (milligrams)—one to two tablets or capsules—every four to six hours. Children between the ages of 6 and 11 can be given Benadryl at a maximum dose of 25 mg (one tablet or capsule) every four to six hours. Benadryl can be taken with or without food.

RELATED: What is Benadryl Allergy? | Benadryl Allergy coupons

Benadryl dosage forms and strengths

Benadryl tablets and gel capsules contain 25 mg of diphenhydramine hydrochloride and are typically taken by adults and children 6 years and older. Benadryl Allergy Plus Congestion, however, also contains 10 mg of phenylephrine hydrochloride, a nasal decongestant. Benadryl Allergy Plus Congestion should not be given to children younger than 12 unless directed by a physician.

• Benadryl Allergy Ultratab Tablets: 25 mg diphenhydramine per tablet

• Benadryl Allergy Dye-Free Liqui-Gels: 25 mg diphenhydramine per gel capsule

• Benadryl Allergy Plus Congestion: 25 mg diphenhydramine/10 mg phenylephrine per tablet

Benadryl dosage for adults

The standard adult Benadryl dose is one to two tablets or gel capsules (25-50 mg) every four to six hours.

• Standard Benadryl dosage for adults: One to two tablets/capsules (25-50 mg) every four to six hours.

• Maximum Benadryl dosage for adults: Two tablets/capsules (50 mg) every four hours to a maximum of 12 tablets (300 mg) in 24 hours.

Benadryl dosage for children

Benadryl dosages may be based on age or weight in children. Children’s Benadryl Allergy is more suitable for children between the ages of 6 and 11. Containing half the dose of diphenhydramine (12.5 mg) as Benadryl Allergy, Children’s Benadryl Allergy is sold in child-friendly liquid and chewable tablet formats.

RELATED: What is Children’s Benadryl? | Children’s Benadryl coupons

Benadryl (the adult formulation) may be given to children between the ages of 6 and 11, but should not be given to children younger than 6. Although Benadryl Allergy may be used to relieve insomnia in children 12 or older, it should not be used as a sleep aid in children younger than 12.

• Standard Benadryl dosage for children younger than 6: Do not give unless directed by a physician.

• Standard Benadryl dosage for children ages 6 to 11: One tablet/capsule (25 mg) every four to six hours.

• Maximum Benadryl dosage for children ages 6 to 11: One tablet/capsule (25 mg) every four hours to a maximum of six tablets (150 mg) in 24 hours.

Note: Children between the ages of 6 and 11 should be not given Benadryl Allergy Plus Congestion except under the direction of a pediatrician.

Benadryl dosage for allergy symptoms

Benadryl relieves symptoms caused by allergies, hay fever, or the common cold including runny nose, congestion, sinus pressure, sneezing, rash, watery or itchy eyes, and itchy nose. Benadryl is also indicated to relieve itchy skin (pruritus) caused by histamine release due to an allergic reaction (contact dermatitis), hives (urticaria), or insect bites.

• Adults and adolescents (12 years and older): 25-50 mg every four to six hours.

• Pediatric patients (6-11 years of age): 25 mg every four to six hours.

• Renally impaired patients:

  • Creatinine clearance 10-30 mL/min: No adjustment

  • Dialysis: No adjustment and no supplement

• Other cautions: Ask a doctor before taking Benadryl if you have one of the following health conditions:

  • Ocular hypertension or glaucoma

  • Hyperthyroidism

  • Cardiovascular disease

  • High blood pressure

  • Asthma or COPD

  • GI obstruction or peptic ulcer disease

  • Enlarged prostate

  • Bladder neck obstruction

Benadryl dosage for motion sickness

Benadryl may be used to prevent and treat motion sickness.

• Adults and adolescents (12 years and older): 25 to 50 mg 30 minutes before travel and every six to eight hours during travel.

• Pediatric patients (6-11 years of age): 12.5 to 25 mg 30 minutes before travel and every six to eight hours during travel.

Benadryl dosage for insomnia

Benadryl may be used for the occasional relief of insomnia or travel-related sleeplessness in adults and adolescents 12 years or older.

• Adults and adolescents (12 years and older): 25 to 50 mg 30 minutes before bedtime.

• Pediatric patients (6-11 years of age): Do not give unless directed by a physician.

Benadryl dosage for pets

Benadryl is not approved for use in pets, but veterinarians do give generic diphenhydramine to dogs, cats, and large animals for the treatment of allergic reactions, nasal allergies, itching, hives, motion sickness, and anxiety problems. Veterinarians also use diphenhydramine to treat some cancers (mast cell tumors), shock, life-threatening allergic reactions, and other conditions

The standard veterinary dosage is 2 to 4 mg of diphenhydramine for each kilogram of body weight (1 to 2 mg per pound) given two or three times per day. However, consult a veterinarian before giving your pet Benadryl or any other OTC medication.

RELATED: How to treat allergies in cats and dogs

How to take Benadryl

For healthy adults and children 12 or older, take one to two tablets or capsules by mouth every four to six hours or as directed by a healthcare provider. Benadryl can be taken with or without food.

• Follow the instructions on the medicine label if you are using this medicine without a prescription.

• If you are using this medicine with a prescription, the prescribing doctor will tell you how much medicine to use. Do not use more than directed.

• Swallow the tablet or gel capsule whole. Do not crush, break, or chew it.

When taking or administering Benadryl, you may want to consider the following safety and effectiveness tips:

• Always check the expiration date. If the medicine has passed its expiration date, dispose of it safely and purchase a new box.

• Store Benadryl at room temperature (68˚-77˚F)

• Check all other medications that you or your child are taking to make sure they do not also contain diphenhydramine or phenylephrine. Both are commonly found in combination cold, flu, or allergy medications. Pay particular attention to topical itch medications that may contain diphenhydramine. These drugs—including topical diphenhydramine—should never be used with Benadryl.

• Do not take Benadryl with alcohol or sedatives.

• People who have glaucoma, breathing problems due to emphysema or chronic bronchitis, or difficulty urinating due to an enlarged prostate should talk to a doctor before taking Benadryl.

• Women who are pregnant or breastfeeding should seek medical advice before taking Benadryl.

• Although Benadryl is approved for children 6 years or older, Benadryl Allergy should not be used as a sleep aid in children younger than 12. 

• For motion sickness, take Benadryl 30 minutes before traveling or exposure to motion. If you are going on a long trip, take the next doses every six to eight hours.

• For each dose, record the time in a diary or schedule to ensure that the next dose is not given too early.

• Benadryl is a sedative, so do not operate machinery or drive if you feel tired, woozy, or unfocused. It’s a good idea to remove obstacles and hazards in the home before taking diphenhydramine.

Benadryl dosage FAQs

How long does it take Benadryl to work?

Taken as directed, Benadryl Allergy usually starts working 30 minutes after being swallowed and reaches peak levels in the body in approximately two hours. In general, food does not affect the absorption of Benadryl or reduce its effectiveness. However, regular use of Benadryl can lead to tolerance. Over time, the standard dose may gradually lose effectiveness.

How long does Benadryl stay in your system?

At the recommended dosage, the effects of Benadryl should last four to six hours, but this will vary. As a general rule, the amount of time Benadryl stays in the system increases with age. 

Healthcare professionals measure how long a drug stays in the body by half-life, which is the time it takes for the body to eliminate half the amount of a drug in the body. The half-life of diphenhydramine in children is four to seven hours (five hours average). For adults, the half-life is seven to 12 hours (nine hours average). For seniors, the half-life ranges from nine to 18 hours (average: 13.5 hours).

What happens if I miss a dose of Benadryl?

There is no problem missing a dose of Benadryl. Take the missed dose at any time. The dosing schedule will reset, so wait at least four hours before taking the next dose. Do not take extra medicine to make up for a missed dose.

How do I stop taking Benadryl?

Benadryl can be used regularly to treat allergic reactions, insomnia, or motion sickness. It should be used only occasionally as a sleep aid. Diphenhydramine is sometimes abused. Chronic use of Benadryl, especially to relieve anxiety or sleeplessness, may result in dependence and produce withdrawal symptoms if Benadryl is rapidly discontinued. High doses of Benadryl can cause serious heart problems, seizures, coma, and death. Before discontinuing Benadryl, talk to a healthcare provider about tapering the Benadryl dose or using alternative medications or therapies for reducing anxiety or treating insomnia.

You should discontinue Benadryl and consult a healthcare provider if you experience excessive nervousness, sleepiness, allergic reactions, or if symptoms do not improve after seven days.

What can be used instead of Benadryl Allergy?

Healthcare professionals usually discourage the use of first-generation antihistamines such as diphenhydramine, the active ingredient in Benadryl. Second-generation antihistamines are equally as effective as diphenhydramine without causing as much sedation or drowsiness. Instead of Benadryl Allergy, you can choose several over-the-counter second-generation antihistamines such as Claritin (loratadine), Alavert (loratadine), Allegra (fexofenadine), Zyrtec (cetirizine), and Xyzal (levocetirizine). 

What is the maximum dosage for Benadryl?

The maximum dose is 50 mg (two tablets or gel capsules) every four hours to a maximum of 300 mg (12 tablets or gel capsules) in any 24-hour period for adults and adolescents 12 or older.

For children between the ages of 6 and 11, the maximum dosage is 25 mg (one tablet or gel capsule) every four hours not to exceed 150 mg (six tablets or capsules) in any 24-hour period.

What interacts with Benadryl?

Foods do not interfere with the absorption or effectiveness of Benadryl. 

Several OTC and prescription drugs can interact with Benadryl, and some may reduce Benadryl’s effectiveness. Drugs that depress or slow down the central nervous system such as tranquilizers, alcohol, or sedatives may enhance Benadryl side effects such as drowsiness, dizziness, sedation, dry mouth, and blurred vision. Always talk to a healthcare provider before combining Benadryl Allergy with central nervous system depressants or other medications.

Benadryl Allergy Plus Congestion also contains phenylephrine, a stimulant. When taken with monoamine oxidase inhibitors (MAOIs), a family of drugs that includes certain types of antidepressants, antibiotics, and Parkinson’s medications, phenylephrine can cause a dangerous and potentially life-threatening rise in blood pressure. Benadryl should not be taken with an MAO inhibitor or within 14 days of discontinuing an MAOI inhibitor. Consult with your doctor, pharmacist, or other healthcare provider if you think a medication you’re taking might be an MAO inhibitor.

Resources:

• Benadryl Allergy

• Children’s Benadryl

• Benadryl dosing guide

• Benadryl Allergy Ultratab Tablets

• Benadryl Allergy Dye-Free Liqui-Gels

• Benadryl Allergy Plus Congestion

• Diphenhydramine compound summary

• Diphenhydramine

• Diphenhydramine for animals

• Chronic diphenhydramine abuse and withdrawal

• Antihistamine dosages

• The pharmacologic management of motion sickness

• FDA warns about serious problems with high doses of the allergy medicine diphenhydramine