Benadryl 12.5 mg 25 mg 50 mg Liquid 12.5 mg per 5 mL

What is Benadryl?

Benadryl is the brand name for diphenhydramine, a first generation antihistamine used to relieve symptoms of allergies, hay fever, the common cold, and mild allergic reactions such as hives or itching. It can also be used short term as a nighttime sleep aid and to help prevent or treat motion sickness. Available forms include 12.5 mg, 25 mg, and 50 mg tablets or capsules, and a liquid containing 12.5 mg per 5 mL for children or people who cannot swallow pills.

Diphenhydramine works quickly, often within 30 minutes, but it also causes drowsiness, which can be helpful at bedtime but problematic during the day. Because of this sedation, it is not recommended for older adults unless no safer option is available. Many people buy generic diphenhydramine for a lower price, and some buy online from licensed U.S. pharmacies for convenience. Cheap options are fine when the label clearly lists diphenhydramine, the strength, and an expiration date, and when a pharmacist is available for questions.

How It Works

Benadryl blocks histamine H1 receptors in the body. Histamine is a chemical released during allergic reactions that causes itching, swelling, redness, and mucus production. By blocking these receptors, diphenhydramine reduces sneezing, runny nose, watery eyes, itching, and swelling. Its ability to cross into the brain leads to sedation, which is why it can be used for short term insomnia but also why it can impair alertness.

Diphenhydramine also has anticholinergic effects, which can dry up nasal and eye secretions but may cause dry mouth, blurry vision, constipation, and urinary retention in some people. Because it acts quickly, it is sometimes given in emergency settings for allergic reactions alongside other treatments.

What you may notice

Within an hour of taking a dose, most people feel less itching, sneezing, or runny nose. If used at bedtime, sleepiness usually develops within 30 to 60 minutes. For motion sickness, taking a dose 30 minutes before travel can help prevent symptoms.

Dosage Information

Follow your product label or clinician instructions exactly. Do not exceed the maximum daily dose. Avoid combining with other antihistamines, sedatives, or alcohol unless specifically directed.

• Adults and children 12 years and older: 25 mg to 50 mg every 4 to 6 hours as needed. Maximum 300 mg in 24 hours.
• Children 6 to 11 years: 12.5 mg to 25 mg every 4 to 6 hours as needed. Maximum 150 mg in 24 hours.
• Children 2 to 5 years: 6.25 mg to 12.5 mg every 4 to 6 hours as needed. Maximum 37.5 mg to 75 mg in 24 hours depending on weight. Use only liquid with proper measuring device.
• Motion sickness: Take 30 minutes before travel and repeat every 4 to 6 hours as needed, without exceeding the daily maximum.
• Nighttime sleep aid: 25 mg to 50 mg at bedtime, not for more than a few nights unless directed by a clinician.

How to take it

Swallow tablets or capsules with water. Shake liquid well and measure with a marked cup or syringe. If you miss a dose and still have symptoms, you can take it when remembered, but skip it if it is nearly time for your next dose. Do not double up.

Cost and access tips

Generic diphenhydramine is widely available and inexpensive. Buying from licensed pharmacies online can save money. Cheap prices are fine when labeling is clear and expiration dates are valid.

Side Effects

Common effects include drowsiness, dry mouth, dizziness, blurry vision, constipation, and urinary retention. These are more likely at higher doses or in older adults. Sedation can impair driving or operation of machinery, so take the first dose when you can rest.

Less common but important

• Confusion or agitation: Especially in older adults.
• Allergic reaction: Rash, itching, swelling, severe dizziness, or trouble breathing require urgent care.
• Heart rhythm changes: Rare but possible, particularly with overdose.

If severe side effects occur, stop the medicine and seek medical attention. For children, paradoxical excitation—restlessness or nervousness—can happen instead of drowsiness.

Warnings & Interactions

Do not use Benadryl to make a child sleepy. Avoid use in children younger than 2 years unless specifically directed by a clinician. Use with caution in older adults and in people with glaucoma, asthma, chronic lung disease, heart disease, high blood pressure, overactive thyroid, seizure disorders, enlarged prostate, or urinary retention.

Drug interactions

• Alcohol and sedatives: Additive sedation and impaired coordination.
• Other anticholinergic drugs: Increased risk of dry mouth, constipation, urinary retention, and confusion.
• MAO inhibitors: Can prolong and intensify side effects.

Pregnancy and breastfeeding

Benadryl is generally considered low risk for short term use in pregnancy but should be discussed with a clinician. It passes into breast milk and may cause sedation in the nursing infant.

Practical safety tips

Always use the lowest effective dose for the shortest time. Keep away from children and pets. If you buy online, choose licensed pharmacies, verify the active ingredient and strength, and check the expiration date. Cheap pricing is fine when those checks are met.