Getting High on Benadryl: How Much Is Safe?

Benadryl is a brand name over-the-counter antihistamine medication. Histamine is a substance produced by the body in response to the presence of allergens like pollen, animal hair, or dust. Histamine release underlies certain symptoms like sneezing, itchy eyes, scratchy feelings in the nose or throat, runny nose, and difficulty breathing. Antihistamines like Benadryl combat the actions of histamine. Some people may also take Benadryl to reduce similar symptoms when they have a cold. Diphenhydramine is the main ingredient in this drug, and the substance can be found in other over-the-counter medications, too.¹

Although Benadryl is sold without a prescription, the drug can cause drowsiness and sedation. Misuse of the medication may occur because people do not properly read the directions, mix it with alcohol or other intoxicants, or take too much of it at once. Any form of misuse can be dangerous and may result in severe side effects or an overdose. ¹

Just like with a prescription drug, it is important to follow the instructions on the package and only take Benadryl in recommended doses for a short period of time.

What Is Benadryl? How Is It Taken Safely?

Benadryl was the first antihistamine to receive approval from the Food and Drug Administration (FDA). The brand name was acquired by Johnson & Johnson in 2007 and the medication remains a widely-used treatment for allergies and mild cold symptoms.¹

Since the medication has been available for several decades, safe dosage and elimination time are well understood. Benadryl is available in a variety of formulations, including tablets, liquid gels, and chewables. The standard dose of diphenhydramine in brand name Benadryl is 25 mg per dose for adults and 12.5 mg per dose in children’s formulas. For the average healthy adult, elimination half-life ranges from 6.7 to 11.7 hours.² So between 6 to 12 hours after taking Benadryl, half the drug will be eliminated from the body. Within two days, the drug will be completely gone from the body.

Several factors impact how quickly Benadryl is metabolized, including: 3

• Age: Adults over 65 years old and children younger than 12 years old metabolize diphenhydramine more slowly, so lower doses less often are safer.³
• Liver problems: Since the active ingredient in Benadryl is processed through the liver, anyone with decreased hepatic function will have difficulty safely consuming this drug.
• Kidney problems: The kidneys help to process toxins by passing them out through the bladder. People who have decreased renal function may have a tough time metabolizing Benadryl. Urinary pH can also impact how the body processes diphenhydramine.
• Hydration: People who do not drink sufficient water may struggle to eliminate diphenhydramine from their system.
• Low vs. high dose: Even healthy adults who take more than the recommended dose of Benadryl will experience consequences, such as taking longer to metabolize the drug. Taking the recommended dose of Benadryl for longer than recommended may also lead to tolerance as the drug builds up in the body, and that also might increase the medication’s elimination time.
• Other medications: Taking prescription drugs, or other over the counter drugs, along with Benadryl may change how the body metabolizes all the substances together.
• Body weight/mass: Different body types process different amounts of medication at different rates. This is true for prescription drugs, recreational substances like alcohol, and over the counter drugs like Benadryl.

Although Benadryl is sold over the counter without a prescription, the active ingredient is potent and has an impact on the body. In addition to eliminating symptoms of allergies or a cold, it also interacts with other organ systems.

Even when taken as directed, Benadryl can cause side effects which include: 4

• Drowsiness or sleepiness.
• Dry mouth.
• Dryness in the nose or throat.
• Dizziness.
• Nausea or stomach upset.
• Headaches.
• Jitteriness or restlessness.
• Tightness in the chest.
• Muscle weakness.
• Loss of appetite.
• Constipation.

When the recommended amount is consumed, effects peak after about two hours. Within four hours, most effects of the medication wear off. There are still metabolites from diphenhydramine’s breakdown in the body, so taking another dose of Benadryl before the full effects wear off may be dangerous.⁵

Additionally, some people take more than the recommended amount because they want to get high. Benadryl produces mild sedative effects, and in larger amounts, that can feel like intoxication.

However, taking more than 25 mg can be extremely dangerous and is more likely to cause harm than produce any euphoria. ⁵

Benadryl Overdose

Too much Benadryl can lead to an overdose and taking the drug with other potent substances can increase the risk of overdose.

For example, taking other antihistamines that contain diphenhydramine can lead to an overdose. Substances like alcohol or benzodiazepines (e.g., Valium, Xanax, Klonopin, etc.) may dangerously increase Benadryl’s sedative effects.

Muscle relaxants, sedative-hypnotic sleep medications like Ambien, tranquilizers, opioids, and other prescription drugs that are central nervous system (CNS) depressants can also adversely interact with Benadryl. In addition, some types of antidepressants called monoamine oxidase inhibitors (MAOIs) do not mix with antihistamines like Benadryl.³

Symptoms of a Benadryl overdose include: 6

• Enlarged pupils.
• Very dry eyes.
• Blurry vision.
• Ringing in the ears (tinnitus).
• Low blood pressure.
• Rapid heart rate.
• Agitation, rapid mood swings, or restlessness.
• Confusion.
• Seizures.
• Delirium.
• Intense, sudden depression.
• Extreme drowsiness.
• Passing out or falling asleep.
• Nervousness or paranoia.
• Physical tremors.
• Unsteady gait, loss of balance, or inability to walk.
• Dry, red skin.
• Nausea or vomiting.
• Inability to urinate.

Attempting to Get High on Benadryl Can Be Extremely Dangerous

Benadryl is not effective as an intoxicant.Taking more than the recommended dose is more likely to lead to an overdose and uncomfortable side effects rather than euphoria. More than 500 mg, which is more than 40 times the recommended dose, may lead to a state of delirium, hallucinations, and other overdose symptoms. Anecdotal evidence about diphenhydramine highs indicates that the effects are more often uncomfortable and unsettling instead of enjoyable.

Attempts at getting high on Benadryl may be indicative of larger issues with addiction or substance abuse. Because Benadryl is easy to acquire, it may be the first drug abused by an adolescent, or it could be a drug abused after struggling with other substances. Regardless, it is important to get help ending substance abuse.

There are many risks in taking Benadryl long term, or mixing it with another drug or medication. If you have been abusing the prescribed dosage for Benadryl, it’s important to be informed about other potential signs that could lead to addiction.

If you or someone you love is struggling with substance abuse issues and are unsure of where to turn, call us today at . River Oaks, one of American Addiction Centers’ Florida rehab centers, is ready to help you overcome addiction and find long-term recovery. Call us today at to learn more about addiction treatment near you.

You aren’t alone. You deserve to get help.

We are here to help you get sober and learn how to stay that way. Retreat to the sunny climate near Tampa, Florida for a stay at the gold standard of treatment facilities. At River Oaks, we offer customized care plans to help you on your recovery journey at our beautiful Hillsborough County campus.

What is the max dose of diphenhydramine for adults?

Medically reviewed by Carmen Pope, BPharm. Last updated on Oct 4, 2021.

I took two 50mg capsules thinking they were 25mg each (that is I took 100mg instead of 50mg) and it was the only thing that put me into a nice 6 hour sleep which I have not had for weeks! If it is acceptable I will try to take this to finally get some good sleep!

The maximum oral dose of diphenhydramine for adults is generally reported as 100mg for a single dose or no more than 300mg in 24 hours, but this can vary depending on what condition diphenhydramine is being used for, the salt of diphenhydramine used (there are two salts available in the United States, diphenhydramine citrate and diphenhydramine chloride), the age of the person, how much diphenhydramine they have tolerated before, and if they are on any interacting medications. Taking too much diphenhydramine can be fatal.

Diphenhydramine is one of the most abused medications in the United States and a 2016 study found that diphenhydramine overdosage accounted for 3.2% of all overdosage deaths in the United States and ranked among the top 15 drugs most frequently involved in drug overdose deaths in the United States. Most diphenhydramine intoxication/overdose cases occur in children ages 6 years or younger. Children who have taken or been given more than 7.5mg/kg of diphenhydramine should be taken to a healthcare facility for observation because they require medical supervision and management. Diphenhydramine overdose or intoxication can be either accidental or intentional.

What is the maximum dose of diphenhydramine for sleep?

When used as a sleep aid the maximum recommended dosage is 76mg for diphenhydramine citrate or 50mg for diphenhydramine hydrochloride. Although diphenhydramine is commonly used for sleeping it is not recommended because it prevents the brain from achieving restorative deep REM sleep and tends to cause anxiety or a “hangover” effect, which causes a person to feel drowsy the next day. Alternatives, such as zolpidem, are preferred as a sleep aid.

Taking diphenhydramine as a sleep aid for more than 7 to 10 nights is not recommended, because you will gain tolerance to it.

Diphenhydramine should never be given to children to help them sleep and is best not given to children younger than 12 years of age without the direction of a physician. Use in children under 6 years old should be avoided. Long-acting tablets or capsules should never be given to children.

What are the symptoms of diphenhydramine overdose or toxicity?

Diphenhydramine can be harmful in large amounts. Symptoms of a diphenhydramine overdose include:

• Blurred vision
• Confusion
• Dry mouth
• Dry skin
• Drowsiness
• Hallucinations (seeing or hearing things that aren’t there)
• Heart rhythm disturbances such as QT prolongation
• Nausea and/or vomiting
• Nervousness
• Psychosis
• Seizures
• Sleepiness
• Tremor
• Unsteadiness.

Recovery from a diphenhydramine overdose is likely if the person survives the first 24 hours but in some people, serious heart rhythm disturbances may occur, which can cause death.

What medicines contain diphenhydramine?

Diphenhydramine may be found in many medicines, sometimes in combination with other ingredients such as acetaminophen or ibuprofen, for example:

• Advil PM
• Aleve PM
• Bayer PM
• Benadryl
• Dimetapp
• Ivarest
• Nytol
• Sominex
• Tylenol PM
• Unisom.

What brands contain diphenhydramine hydrochloride and diphenhydramine citrate?

Common brands containing diphenhydramine and the salt they contain include:

• Advil PM (diphenhydramine citrate)
• Aleve PM (diphenhydramine hydrochloride)
• Bayer PM (diphenhydramine citrate)
• Benadryl (diphenhydramine hydrochloride)
• Dimetapp (diphenhydramine hydrochloride)
• Ivarest (diphenhydramine hydrochloride)
• Sominex (diphenhydramine hydrochloride)
• Tylenol PM (diphenhydramine hydrochloride)
• Unisom (diphenhydramine hydrochloride).

References

• Diphenhydramine overdose Mt Sinai.https://www.mountsinai.org/health-library/poison/diphenhydramine-overdose
• Huynh DA, Abbas M, Dabaja A. Diphenhydramine Toxicity. [Updated 2021 May 8]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2021 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK557578/
• Zhang D, Tashiro M, Shibuya K, Okamura N, Funaki Y, Yoshikawa T, Kato M, Yanai K. Next-day residual sedative effect after nighttime administration of an over-the-counter antihistamine sleep aid, diphenhydramine, measured by positron emission tomography. J Clin Psychopharmacol. 2010 Dec;30(6):694-701. doi: 10.1097/jcp.0b013e3181fa8526. PMID: 21105284.
• Katayose Y, Aritake S, Kitamura S, Enomoto M, Hida A, Takahashi K, Mishima K. Carryover effect on next-day sleepiness and psychomotor performance of nighttime administered antihistaminic drugs: a randomized controlled trial. Hum Psychopharmacol. 2012 Jul;27(4):428-36. doi: 10.1002/hup.2244. PMID: 22806823.

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Medical Disclaimer

Quick Answer: How much Benadryl is safe for a dog?

According to the Merck Veterinary Manual, the safe dosage is 2-4 milligrams per kilogram of body weight, or 0. 9 to 1.8 milligrams per pound. This amount can be administered two to three times a day, depending on your dog’s symptoms.

Benadryl is commonly used to treat itching in dogs caused by skin allergies and also reduces many other allergy symptoms, including: hives. Edema and inflammation. Redness.

With proper pet safety instructions, proper dosage, and guidance from your veterinarian, yes, Benadryl can be safe for dogs. With all medications, please observe your dog’s behavior during the first medication trial. Before proceeding, make sure your dog is not reacting abnormally to the medication.

Benadryl may cause severe drowsiness, dry mouth or urinary retention in the dog, and potentially cause gastrointestinal disturbances such as diarrhea and/or vomiting.

According to the Merck Veterinary Manual, the safe dosage is 2-4 milligrams per kilogram of body weight, or 0.9 to 1.8 milligrams per pound. This amount can be administered two to three times a day, depending on your dog’s symptoms.

This medicine will work quickly, in about 1-2 hours, and this should be followed by an improvement in clinical signs.

Oatmeal is an age old remedy for dry, itchy skin that is safe to use on our dog friends too! In fact, most hypoallergenic dog shampoos contain oatmeal as an active ingredient that soothes and fights irritation. Start by grinding plain oatmeal into a powder to sprinkle in your dog’s warm bath.

When dog scratches get out of hand, it’s often the result of food allergies or environmental factors, including mold and pollen. Dogs can also develop a skin irritation called contact dermatitis when in contact with substances such as pesticides or soaps. Boredom or anxiety.

The standard dose of oral Benadryl for dogs is 1 mg per pound of body weight 2-3 times daily. Most diphenhydramine tablets have a 25mg dose, which is about the size of a 25-pound dog. But the safest way to give the correct dose is to ask your veterinarian.

Never give your dog too much Benadryl – an overdose is possible. Abuse of the drug can lead to fatal diphenhydramine poisoning, so always consult your veterinarian if you are unsure of the correct dosage. Signs of an overdose include constipation, agitation, dilated pupils, seizures, and rapid heartbeat.

Diphenhydramine-only Benadryl is a human drug that can also be used as an additional labeling drug for dogs. It is very important to check the ingredients on the label as some strains contain additional ingredients such as phenylephrine that may be harmful to your pet.

You can give your dog Benadryl (diphenhydramine) 2-3 times a day at a rate of 1 mg per pound of body weight. For example, a 12-pound dog may receive 12 mg, which is equal to one child’s dose of Benadryl or ½ an adult’s dose. A 50 lb dog will need 50mg or two of adult Benadryl. Benadryl may cause drowsiness.

Benadryl begins to work in 15-30 minutes, and its maximum effect occurs in 2-4 hours. The adult dose for sedation is 25 to 50 milligrams.

It is true that Benadryl can relieve symptoms in some dogs, but the sedative effects are mild and not as pronounced in dogs as they are in humans. Thus, in general, Benadryl does not usually help dogs struggling with anxiety or phobias.

Antihistamines. Diphenhydramine (Benadryl®), cetirizine (Zyrtec®), and loratadine (Claritin®) are commonly antihistamines that relieve allergy symptoms or counter allergic reactions. Antihistamines are generally safe, but they can cause drowsiness in some dogs and hyperactivity in others.

Is expired Benadryl safe?

If a medicine is past its expiration date, throw it away and replace it with a new product, Benadryl says. However, according to The Allergy Clinic.

The expiration date on medicine vials is the last date the manufacturer is prepared to guarantee safety and efficacy. After the expiration date, nothing happens for the drug to lose its effectiveness, explains the Harvard Medical School Family Health Guide. Many medicines, especially those kept in unopened original containers, can remain effective for many years after the expiration date.