Disclaimer: This article is for informational purposes only and does not constitute medical advice. It is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of a physician or other qualified health provider with any questions you may have regarding a medical condition.
Overview
Benadryl is a brand name for diphenhydramine, an older (first-generation) antihistamine. In Canada it is sold without a prescription as 25 mg caplets and in other forms, including children's products.
Benadryl Allergy products are labelled for the temporary relief of allergy symptoms and hives. Diphenhydramine causes marked drowsiness, so it is not a good choice before driving or work that needs alertness. Newer antihistamines that cause less drowsiness are also available.
Benadryl is sold without a prescription in Canada. If your symptoms do not improve, or you are not sure it is safe for you, BC residents can speak with a BC-licensed doctor by phone through Avee Health.
In Canada, Benadryl Allergy caplets are labelled to temporarily relieve:
- Sneezing and a runny or itchy nose
- Itchy, watery eyes and an itchy throat
- Hives and itchy skin
Benadryl is not a treatment for a severe allergic reaction (anaphylaxis). If you have an epinephrine auto-injector, use it, and call 911 for trouble breathing, throat swelling or fainting. Benadryl Allergy products are not labelled as sleep aids.
Diphenhydramine
First-generation antihistamine
allergy
Over-the-counter
Available
How Benadryl Works
Histamine is a chemical the immune system releases during an allergic reaction. It causes sneezing, itching, a runny nose, watery eyes and hives. Diphenhydramine is an antihistamine, which means it blocks the action of histamine and eases these symptoms.
Diphenhydramine also causes marked drowsiness. This is why the same ingredient is used in some non-prescription sleep aids. For allergy symptoms, the label allows a dose every 4 to 6 hours as needed.
Dosage Instructions of Benadryl
Follow the package directions. The Canadian label for Benadryl Allergy 25 mg caplets says:
- Adults and children 12 years and over: 1 to 2 caplets (25 mg to 50 mg) every 4 to 6 hours as needed
- Maximum: 8 caplets in 24 hours
- Children under 12: do not use the caplets. Use a children's product and follow the directions for the child's age on that package, measuring with the device supplied.
Other Benadryl products have different strengths, so read the label of the product you have. Check with a doctor or pharmacist before giving an antihistamine to a young child.
Benadryl is taken only when you have symptoms, so there is no missed dose to make up. Do not take more than the recommended dose or use it for a long time unless a doctor advises it. Stop and ask a doctor if symptoms get worse, last more than 7 days, or new symptoms appear.
If someone takes too much, call a poison control centre or get medical help right away, even if there are no symptoms.
Storage Instructions
Store at room temperature as directed on the label. Keep all Benadryl products out of the reach of children.
Side Effects of Benadryl
The Canadian label does not give percentages. Possible effects include:
- Marked drowsiness
- Excitability, especially in children
- Dry mouth, blurred vision or trouble passing urine
Get medical help right away if you have:
- Signs of an allergic reaction to the medicine, such as trouble breathing or swelling
- A seizure, hallucinations, confusion or a very fast heartbeat
- A possible overdose, especially in a child, even if there are no symptoms
Important Safety Information About Benadryl
- Drowsiness and driving: marked drowsiness may occur. Do not drive, operate machinery or do anything that needs mental alertness while using Benadryl.
- Alcohol: avoid alcoholic drinks. Alcohol, sedatives and tranquilizers increase the drowsiness.
- Do not use Benadryl if you are allergic to diphenhydramine or any ingredient, or with any other product that contains diphenhydramine, even one used on the skin.
- Ask a doctor or pharmacist first if you have glaucoma, a breathing problem such as emphysema, chronic bronchitis or chronic asthma, trouble passing urine because of an enlarged prostate, or a cough with a lot of mucus.
- Pregnancy and breastfeeding: ask a doctor or pharmacist before use.
- Children: diphenhydramine can cause excitability instead of drowsiness. Use only products made for the child's age, and keep all diphenhydramine products locked away, because accidental swallowing can cause serious poisoning.
- Older adults: drowsiness and confusion can raise the risk of falls. Ask a doctor or pharmacist before use.
- Do not take more than the label dose or use it for a long time unless a doctor advises it. Misuse and overdose can be life-threatening.
Drug Interactions
Tell your pharmacist about everything you take, including non-prescription products. The Canadian label warns about:
- Alcohol: increases drowsiness. Avoid it.
- Sedatives and tranquilizers, such as sleeping pills and medicines for anxiety: increase drowsiness. Ask a doctor or pharmacist first.
- Other antihistamines: ask a doctor or pharmacist first.
- Any other product with diphenhydramine, even one used on the skin: do not use together. Some sleep aids, cough and cold products and anti-itch products contain it.
Brands & DIN Number of Benadryl
Brand Names
Benadryl
Key Takeaways
- 1Benadryl is diphenhydramine, an older antihistamine sold without a prescription in Canada for allergy symptoms and hives.
- 2For people 12 and over, the label dose is 1 to 2 caplets (25 mg to 50 mg) every 4 to 6 hours, with no more than 8 caplets in 24 hours.
- 3It causes marked drowsiness. Do not drive or operate machinery while using it, and avoid alcohol.
- 4Do not combine it with any other product that contains diphenhydramine, including skin products and sleep aids.
- 5Ask a doctor or pharmacist first if you have glaucoma, a chronic breathing problem or an enlarged prostate, or if you are pregnant or breastfeeding.
- 6Children under 12 need a children's product. Keep all diphenhydramine products out of children's reach, because overdose can be serious.
- 7It does not replace epinephrine in a severe allergic reaction. Call 911 for trouble breathing or throat swelling.
Frequently Asked Questions
Do I need a prescription for Benadryl in Canada?
How much does Benadryl cost in Canada, and does BC PharmaCare cover it?
Does Benadryl make you drowsy, and can I drive after taking it?
Can I take Benadryl to help me sleep?
Can I drink alcohol while taking Benadryl?
Can I take Benadryl while pregnant or breastfeeding?
What is the difference between Benadryl and newer antihistamines like Claritin or Reactine?
When should I talk to a doctor?
Avee Editorial
Avee Editorial Team