Standard Benadryl tablet strength
A standard over-the-counter Benadryl tablet contains 25 milligrams of diphenhydramine hydrochloride, which is the active ingredient that causes drowsiness and reduces allergy symptoms. This is the most common strength you will find on pharmacy shelves in the United States.
Benadryl also makes a 50-milligram tablet, sold as Benadryl Extra Strength, which is twice the standard dose. The 50 mg version is meant for people who need stronger symptom relief, though it also causes more drowsiness. Both come in the same small, round tablet form.
The label on your box will always show the milligram strength clearly on the front. If you have picked up a Benadryl product and are unsure which strength you have, check the box or the blister pack — it will say either "25 mg" or "50 mg" near the product name.
Key Takeaways
- Standard Benadryl tablets contain 25 mg of diphenhydramine, while Extra Strength contains 50 mg per tablet.
- The strength is printed on the front of the box and on the individual tablet blister pack.
- Dosing instructions on the label tell you how many tablets to take and how often, based on the strength you have.
- Children's Benadryl liquid and chewables use different strengths than tablets, so do not assume the dose is the same.
- Always read the label before taking any dose, because taking the wrong strength or too many tablets can cause serious side effects.
Why tablet strength matters for dosing
The number of milligrams in your tablet determines how many tablets you should take per dose. If you have the 25 mg tablet, the standard adult dose is one or two tablets every four to six hours, up to six doses in 24 hours. If you have the 50 mg Extra Strength tablet, the standard dose is one tablet every four to six hours, up to four doses in 24 hours.
Taking the wrong number of tablets — or mixing up which strength you have — can lead to overdose. Diphenhydramine overdose causes extreme drowsiness, confusion, rapid heartbeat, and in severe cases, seizures or loss of consciousness. This is why the label instructions matter: they are written for the specific strength in that box.
If you are unsure which strength you have or how many tablets to take, call your pharmacist or poison control before taking any dose. Your pharmacist can tell you in seconds what is safe for your age and health.
Other Benadryl products and their strengths
Benadryl makes products beyond tablets, and they do not all contain the same strength. Benadryl liquid (for adults) contains 12.5 mg per teaspoon, so you would need two teaspoons to equal one 25 mg tablet. Benadryl cream and gel contain diphenhydramine but are meant to be rubbed on skin, not swallowed, so the milligram amount works differently.
Children's Benadryl comes as a liquid or chewable tablet with much lower strengths — typically 12.5 mg per dose — because children's bodies process the drug differently than adults. Never give a child an adult Benadryl tablet, even if you cut it in half, because the dose will not be right for their weight and age.
If you are buying Benadryl for a child, an older adult, or someone with a medical condition, the pharmacist should confirm the correct product and dose before you leave the store. The box label is your guide, but a pharmacist can answer questions the label cannot.
Reading the label to confirm strength
The front of a Benadryl box will say either "Benadryl" (for 25 mg) or "Benadryl Extra Strength" (for 50 mg). Below the product name, you will see the strength printed in large text: "25 mg" or "50 mg per tablet." This is the most reliable way to know what you have.
The back of the box contains the Drug Facts label, which lists the active ingredient (diphenhydramine hydrochloride), the strength per tablet, and the dosing instructions for adults and children. If the label is hard to read or missing, do not take the tablet — return it to the pharmacy and ask for a replacement box with a clear label.
What happens if you take too much
Taking more than the label recommends — for example, taking three 25 mg tablets when the label says one or two — can cause overdose symptoms. These include severe drowsiness, dry mouth, blurred vision, confusion, rapid or irregular heartbeat, and difficulty urinating. In rare cases, very high doses can cause seizures or coma.
If you or someone else has taken too much Benadryl, call Poison Control at 1-800-222-1222 (available 24 hours in the United States) or go to the emergency room. Have the box or bottle with you so you can tell them the exact strength and how many tablets were taken. Poison Control can tell you whether you need medical care.
Frequently Asked Questions
Can I cut a 50 mg tablet in half to get 25 mg?
Most Benadryl tablets are not scored (they do not have a line down the middle), so cutting them is difficult and the halves may not be equal. If you need a 25 mg dose and have 50 mg tablets, ask your pharmacist for 25 mg tablets instead, or use the liquid form, which you can measure more accurately.
Is the strength the same in generic diphenhydramine tablets?
Yes. Generic diphenhydramine tablets sold at any pharmacy contain the same strength as name-brand Benadryl — either 25 mg or 50 mg per tablet. The label will show the strength clearly. Generic and brand-name versions work the same way; the only difference is the price and the box design.
What if I took one tablet and I am not sure if it was 25 mg or 50 mg?
Call your pharmacist or Poison Control and tell them when you took it and what symptoms you are having. If you took it within the last hour, they may recommend activated charcoal or other steps. If you feel fine and took it within the normal dose range, you are likely safe, but a pharmacist can confirm.
Do I need a prescription for Benadryl tablets?
No. Benadryl 25 mg and 50 mg tablets are over-the-counter medications sold without a prescription at any pharmacy, grocery store, or drugstore. You do not need to ask a pharmacist to buy them, but you can ask one for information on whether they are right for you before you buy.