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What are the Uses and Possible Side Effects of Benadryl?

benadryl uses and side effects


Antihistamines are medicines used to relieve symptoms of allergies, like hay fever, conjunctivitis, hives and reactions to bites or stings from insects. Moreover, they are sometimes used to defend against motion sickness and as an interim treatment for insomnia.

Most antihistamines can be acquired from pharmacies, but some are only available on prescription.

 As a chemical engineer, George Rieveschl discovered diphenhydramine in 1940 at the University of Cincinnati while researching muscle relaxants.

Diphenhydramine, brand name Benadryl®, is one of the oldest and most frequently used over-the-counter medications for children. For prescription use, Benadryl was approved by the Food and Drug Administration (FDA) In 1946. 

BENADRYL should only be used as directed by doctors. Mistreatment with this product can lead to serious side effects with long-lasting or even life-threatening consequences.

Parents and pediatricians routinely give Benadryl to infants and children for multiple reasons. Misconceptions surrounding Benadryl are common – We will cover some details and clear your question regarding the usage of Benadryl.

Can you use Benadryl for Anxiety? If you are suffering from Anxiety and don’t like routine medications and you might wonder rather over-the-counter (OTC) medications such as Benadryl might help you to manage your problems.

But there are many questions like, Are they safe to use? Do they work, really? What could be the pros and cons? 

If all the above queries are bothering you, then this article will help answer all of your questions.

What is Benadryl?

Benadryl belongs to a class of drugs called Antihistamines, 1st Generation, and Antiemetic Agents and is used to provide allergy relief and treat allergy symptoms such as sneezing, runny nose, hives, skin rashes, watering eyes, and other cold or allergy symptoms. It is also used to treat motion sickness, induce sleep, and treat certain symptoms of Parkinson’s disease. Benadryl may be prescribed but is normally sold over-the-counter (OTC) and diphenhydramine in its generic form. 

What is Benadryl Used for?

Benadryl is a prescription medicine used for the treatment of the symptoms of 

  • Allergic reactions
    Benadryl temporarily relieves allergy symptoms caused by a natural substance called histamine.
  • Insomnia & Motion Sickness
    The use of diphenhydramine causes drowsiness and impedes the part of the brain which controls nausea. Hence, Benadryl can provide occasional insomnia relief or prevent motion sickness. 
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Benadryl Dosage

Benadryl tablets, Benadryl pills, and gel capsules contain doses of 25 mg of diphenhydramine hydrochloride and are mostly taken by adults and children six years and older. 

Dosage Chart

With the help of this Chart, you will be able to understand Standard and Maximum Dosages against mentioned indication.

IndicationAgeStandard dosageMaximum dosage
Allergy symptoms, common cold symptoms, itching12+1-2 tablets/capsules (25-50 mg) every 4-6 hours12 tablets/capsules (300 mg) in 24 hours
6-111 tablet/capsule (25 mg) every 4-6 hours6 tablets/capsules (150 mg) in 24 hours
<6Not given unless directed by a physicianNot given unless directed by a physician
Motion sickness12+1-2 tablets/capsules (25-50 mg) 30 minutes before travel12 tablets/capsules (300 mg) in 24 hours
6-111 tablet/capsule (25 mg) 30 minutes before travel6 tablets/capsules (150 mg) in 24 hours
<6Not given unless directed by a physicianNot given unless directed by a physician
Insomnia12+1-2 tablets/capsules (25-50 mg) 30 minutes before bedtime12 tablets/capsules (300 mg) in 24 hours
<12Not given unless directed by a physicianNot given unless directed by a physician

Can Benadryl help with Anxiety?

  • Occasionally Anxiety is the result of normal reactions that happen in our lives due to certain stressful situations. Mostly, it’s a momentary feeling. Anxiety might happen from events like public speaking. 
  • Provisional Anxiety happens to everyone and doesn’t hamper our daily life.
  • But, Anxiety Disorders (AD) are more critical and can take a person’s daily happiness. Scientists mostly believe that there may be genetic and environmental causes of anxiety disorders other than individual factors involved.
  • General Anxiety may cause Restlessness, Nervousness, and Difficulty falling asleep.

Some people with the above symptoms may use diphenhydramine for its sedating effects. But remember that the Food and Drug Administration recommends diphenhydramine for use as an anxiety drug. 

Using diphenhydramine for Anxiety is likely not a good idea. Diphenhydramine may be mostly taken as a temporary sleep support for its sedating effects. 

Diphenhydramine may offer short-term relief for a few people who experience occasional sleeplessness from Anxiety. But it has limited benefits as a sleep aid.

Can you take expired Benadryl?

  • An expiry date is a time until which the drug maker can guarantee that the medicine is completely potent and safe to take based on product testing. Expiration dates tell us that we are buying safe medicine. Normally, solid forms, such as tablets and capsules, consider being most stable past their expiration date.
  • Benadryl that has expired six months may work, but only if it has been kept in a dry, cool place away from light in its original container. However, this is an important point and may not be as effective as before. If it has passed its expiration date, then it likely won’t harm you as there has been no history of expired Benadryl causing harm, and there is no sign that it breaks down into harmful components.
  • If you rely on Benadryl to help lower the syndrome of an allergic reaction, it would be advisable to have an ‘in-date’ commodity, so you know it will have its stated capability.

Does Benadryl help with nausea?

  • Benadryl appears to dull the inner ear’s ability to sense motion. They block messages to the part of the brain that controls nausea and vomiting. Now here the question arises how long does Benadryl take to work for nausea? Benadryl is absorbed rapidly in your body. You’ll notice the effects within about 20-30 minutes. The drugs should continue to work for about 4-6 hours. It would be best to take only Benadryl for less time unless your doctor tells you to take it longer.
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Benadryl side effects

This can cause mild or serious side effects depending upon the usage. The undermentioned list contains some of the key side effects. This list may not include all possible side effects.

You can get more information on the possible side effects or tips on how to deal with them by talking with our doctors.

Common side effects

  • Sleepiness
  • Weakness
  • Dizziness
  • Headache
  • Dry mouth

Note: Some of the above effects leave in a couple of weeks. 

Serious side effect

  • Dementia
  • Confusion
  • Seizures
  • Decreased memory
  • Impaired thinking
  • Fast heartbeat

Long-term side effects
Over-the-counter Benadryl is only approved for temporary or short-term use and isn’t recommended for long-term use. Some side effects that may occur after long-term use are:

  • Memory problems and dementia (especially in seniors)
    Blurred vision

Some other side effects are:

  • Dementia
    It can sometimes cause a decrease in memory, confusion, and thinking issues. These side effects are more common in elders.
    In addition, taking Benadryl long-term might increase the risk of dementia. People aged> 65 who took medications such as Benadryl daily for more than three years had an increased risk of dementia.

Benadryl should be used for the shortest time possible. 

  • Hallucinations
    People who take high doses of Benadryl may experience hallucinations. Don’t take any more of the medication in this case. 
  • Restless legs syndrome
    Benadryl may worsen symptoms of restless legs syndrome.
  • Weight gain
    Weight gain can happen in some cases who use diphenhydramine. 
  • Constipation
    Regular usage of Benadryl can cause constipation.
  • Driving warning
    Benadryl can impair your driving ability because it can make you very sleepy. If you feel sleepy after taking a dose of it, don’t drive anymore. 
  • Side effects in children
    Generally similar to those in adults, as described above. However, in children, oral or liquid Benadryl can sometimes become the reason for unexpected side effects such as
    Irritability or agitation
    Trouble sleeping
    Muscle spasms
  • In newborns, oral Benadryl can cause:
    Sudden infant death
    Trouble breathing

Due to the risk of worse side effects in children, oral Benadryl products are only approved for use in children six years and older.

Consult our doctor right away if you have any serious side effects, including mental or mood changes, difficulty urinating, fast or irregular heartbeat, seizures, rash, itching or swelling, severe dizziness and trouble breathing.

Risks and Drug Interactions

  • Four hundred fourteen medications and drugs interact with Benadryl (diphenhydramine), eight disease interactions and 1 Benadryl and alcohol/food interaction. Of the total drug interactions, 13 are major, 399 are moderate, and 2 are minor.
  • Benadryl can interact with the blood pressure medications metoprolol succinate (Toprol-XL) and metoprolol tartrate (Lopressor), as described below:
  • Benadryl may cause an increase in the amount of metoprolol in your body. This, in turn, can increase the risk of side effects from metoprolol, including slow heart rate and low blood pressure.
  • Tell your doctor if you use Benadryl during treatment for high blood pressure. They may recommend taking a lower dose of metoprolol tartrate or succinate to prevent possible side effects.
  • Benadryl can interact with other antihistamines, as described below.
    Benadryl can enhance your risk of side effects from other antihistamines like loratadine (Claritin), meclizine (Antivert),  hydroxyzine (Vistaril), cetirizine (Zyrtec), promethazine (Promethegan) Taking more than one form of Benadryl may also increase your risk of side effects.
    Due to the risk of increased side effects, your doctor may recommend avoiding other antihistamines when using Benadryl. This includes other Benadryl products.
  • Benadryl may have other interactions. They could occur with supplements, foods, vaccines, or even lab tests. See below for details.
  • There are currently no reports of Benadryl interacting with herbs, vitamins and vaccines. But interactions with herbs will be recognized in the future.
Concerned if any of Your Medications or Foods Interact with Benadryl? Consult one of Our Doctors Now.

What is the Maximum Dosage of Benadryl?

Benadryl dosage depends on several factors. Some of them are as follows:

  • The form of Benadryl you’re taking
  • Condition you’re using Benadryl to treat
  • Your age

As a rule, you should use the smallest dosage that provides the desired effect.

Oral Benadryl products should be used at most six times each day. 

Adults and children > 12 years, the maximum dosage is 300 mg each day. 

Children ages 6-12 years, the maximum dosage is 150 mg each day.

Adults or children, these products, such as the cream, gel, and spray, shouldn’t be used more than four times per day on the skin.

If you need to take an antihistamine long-term, consult our doctor for other options.

Overdose of Benadryl

Side effects of Benadryl overdose may include severe drowsiness, seizures, and widened pupils. In children, mental/mood changes (such as restlessness, irritability, and hallucinations) may occur before drowsiness.

Diphenhydramine can be harmful to a large extent. Symptoms of a diphenhydramine overdose may include:

  • Drowsiness
  • Hallucinations 
  • Blurred vision
  • Confusion
  • Dry mouth
  • Dry skin
  • Nervousness
  • Psychosis
  • Seizures
  • Sleepiness
  • Tremor
  • Unsteadiness
  • Heart rhythm disturbances 
  • Nausea and vomiting

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

Benadryl precautions

Benadryl may not be a good choice if you have certain medical conditions. Examples of these conditions include

  • Asthma. 
  • Taking Benadryl can sometimes cause the thickening of mucus in the trachea, known as the windpipe. Asthma attacks may get worsen.
  • Bladder or prostate problems. 
  • Symptoms of urinary retention get worse.
  • Dementia. 
  • It can cause memory problems. 
  • Glaucoma. 
  • Benadryl can worsen symptoms of glaucoma. 
  • Heart problems and high blood pressure
  • Although it is rare, Benadryl can sometimes cause heart-related issues such as a fast heartbeat or low blood pressure. These effects may worsen some heart conditions.
  • Liver disease. 
  • Our body breaks down Benadryl in our liver. So, People with liver disease may not be able to channel Benadryl properly, leaving an increased amount of the drug in their bodies. 
  • It can lead to a higher risk of side effects from Benadryl. If you have liver disease, use a lower dosage.

Benedryl should be avoided in the following cases as well:

  • People who wear contact lenses. 
  •  Benadryl can cause dry eyes
  • For seniors
  • higher risk of side effects, especially when it’s used long-term. 
  • Second-generation antihistamines may be a suitable choice for seniors.

FAQs About Banadryl Answered By your Doctor Online Team

How much Benadryl can I take?

Never take more than six doses in 24 hours. Use as directed. Take 1-2 tablets after every 4 to 6 hours or as directed by a doctor.

Is benadryl an antihistamine?

Yes, The first-generation antihistamine diphenhydramine is the main active Benadryl ingredient. 

How long does Benadryl take to work?

It normally takes about 30 minutes to work.

Does Benadryl make you sleepy?

It can induce drowsiness by working against a chemical produced by the central nervous system.

How long does Benadryl’s drowsiness last?

Drowsiness usually wears off 8 hours after a dose.

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