Phenadryl

Phenadryl Uses, Dosage, Side Effects, Mechanism of Action, How Long Does it Take to Work? Phenadryl is a brand name. Its generic name is Diphenhydramine.

Introduction

Phenadryl is a widely used over-the-counter antihistamine that interacts with a wide range of body systems, primarily the central nervous system. It is used to treat ailments such as allergies, motion sickness, insomnia, and some forms of arthritis.

Uses For

Phenadryl is used to treat a variety of ailments, including allergies, motion sickness, hay fever, insect stings, itching, insomnia, hives, sunburn, rashes, colds, and minor pain. It is also used to treat Parkinson’s disease, narcolepsy, and restless leg syndrome.

Mechanism Of Action

Phenadryl acts as a competitive antagonist of histamine H1 receptors, preventing histamine from binding to its receptor sites. This mechanism of action results in a decrease in the actions of histamine, including the symptom relief associated with its use.

How Long Does It Take to Work?

The effects of diphenhydramine can be felt anywhere from 30 minutes to 1 hour after ingestion. The peak of the effect is usually reached between 2 and 4 hours after ingestion.

Absorption

Phenadryl is rapidly and completely absorbed orally, with peak concentrations of the drug in the blood occurring at approximately 1 hour after ingestion.

Route of Elimination

Phenadryl is rapidly metabolized and eliminated from the body, primarily in the urine. Its metabolites are primarily excreted through the urine as well.

Dosage

The dosages of diphenhydramine vary depending on the indication for use and the route of administration. For oral administration: Adults: 25-50mg at bedtime or every 4-6 hours as needed Children age 6-12: 12.5-25mg at bedtime or every 4-6 hours as needed Children age 2-6: 6.25-12.5mg at bedtime or every 4-6 hours as needed For intramuscular administration: Adults: 25-50mg every 6-8 hours as needed For rectal administration: Adults: 25-50mg every 4-6 hours as needed

Administration

Phenadryl can be administered orally, intramuscularly, or rectally. Oral administration is the most common route of administration, followed by intramuscular injection and rectal administration.

Side Effect

Common side effects of diphenhydramine include dry mouth, drowsiness, dizziness, headache, nausea, vomiting, constipation, and blurred vision. Rare side effects may include confusion, chest pain, difficulty urinating, fever, irregular heartbeat, loss of coordination, muscle weakness, rash, seizures, and unusual excitement.

Toxicity

No cases of overdose resulting in death from diphenhydramine alone have been reported. Symptoms of overdose may include drowsiness, agitation, dilated pupils, dry skin, flushed face, hallucinations, nausea, rapid heartbeat, and vomiting.

Precaution

Phenadryl should be used with caution in patients with glaucoma, asthma, coronary artery disease, hypertension, and high thyroid levels. It should also not be used in combination with other sedatives or alcohol.

Interaction

Phenadryl may interact with other medications including sedatives, antacids, antibiotics, antifungals, thyroid medications, and medications used to treat depression or psychotic disorders.

Disease Interaction

Phenadryl may interact with several diseases, including asthma, glaucoma, coronary artery disease, hypertension, and hyperthyroidism. It should be used cautiously in patients with these conditions.

Drug Interaction

Phenadryl may interact with a variety of drugs, including sedatives, antacids, antibiotics, antifungals, thyroid medications, and medications used to treat depression or psychotic disorders. It should be used with caution and under the advice of a physician in combination with other drugs.

Food Interactions

Phenadryl may interact with certain foods, including coffee, tea, alcohol, chocolate, and some sharply flavored fruits and vegetables. These interactions can reduce the effectiveness of the drug or cause adverse side-effects.

Pregnancy Use

Phenadryl should not be used during pregnancy as it may cause harm to an unborn baby. It should be used only if prescribed by a physician and when the potential benefits outweigh the risks.

Lactation Use

Phenadryl should not be used during breastfeeding due to the potential for adverse effects on the newborn. However, it may be used if the potential benefits are deemed to outweigh the risks.

Acute Overdose

Signs of diphenhydramine overdose include drowsiness, agitation, dilated pupils, dry skin, flushed face, hallucinations, nausea, rapid heartbeat, and vomiting. Treatment for an overdose of diphenhydramine may include treatment with activated charcoal, stomach lavage, and supportive care.

Contraindication

Phenadryl should not be used in patients with hypersensitivity or allergy to the drug. In addition, it should not be administered to patients with narrow-angle glaucoma, severe respiratory, hepatic, or renal impairment, and angle-closure glaucoma.

Use Direction

Phenadryl should be taken exactly as prescribed by a physician or pharmacist. For oral administration, the drug should be taken with food or milk to avoid stomach upset. The drug should not be taken more frequently than prescribed or for longer duration of time than recommended.

Storage Condition

Phenadryl should be stored at room temperature, away from heat and light. It should also be kept out of reach of children and away from pets.

Volume Of Distribution

The apparent volume of distribution of diphenhydramine is 0.4 L/kg.

Half-life

The elimination half-life of diphenhydramine is approximately 4-9 hours.

Clearance

The clearance of diphenhydramine is 7.5 mL/minute/kg.

Here you find in details version of Phenadryl

Some Frequently Asked Questions About Phenadryl

What is Phenadryl?

Phenadryl is an antihistamine used to treat symptoms of seasonal allergies, such as sneezing and watery eyes. It is also used to treat motion sickness, insomnia, allergies, and cold symptoms such as sneezing and runny nose.

How long does Phenadryl take to work?

Phenadryl typically begins working in about 15 minutes, with full effects being felt within about 30 minutes.

How long does Phenadryl stay in your system?

Phenadryl can remain in your system for up to four days after taking it.

How often can you take Phenadryl?

Phenadryl should generally be taken no more than every 4-6 hours, and should not be taken more than 6 times a day.

What are the side effects of Phenadryl?

Common side effects of diphenhydramine include drowsiness, dry mouth, constipation, and dizziness.

How does Phenadryl work?

Phenadryl works by blocking the effects of histamine, the chemical your body makes when exposed to allergens. This can help to relieve symptoms such as sneezing and itching.

Can Phenadryl be used to treat nausea?

Yes, in some cases diphenhydramine may be used to treat nausea, although it is not its primary use.

Can I drink alcohol while taking Phenadryl?

No, it is not recommended to drink alcohol while taking diphenhydramine, as the combination can increase the risk of serious side effects.

Can I take Phenadryl for a headache?

No, diphenhydramine is not typically a recommended treatment for headaches. Pain relievers such as ibuprofen or acetaminophen may be more effective.

Is Phenadryl safe to take during pregnancy?

Phenadryl should not be taken during pregnancy unless instructed to do so by a doctor, as it can be dangerous for both mother and baby.

Does Phenadryl help with allergies?

Yes, Phenadryl can help to reduce allergy symptoms such as sneezing, itching, and runny nose.

Can Phenadryl help with insomnia?

Yes, Phenadryl can help to promote sleep and can be used to treat insomnia.

Does Phenadryl help with anxiety?

No, Phenadryl is not typically used to treat anxiety, and can actually make symptoms of anxiety worse. Other medications or therapies may be more effective at treating anxiety.

Can children take Phenadryl?

Yes, in some cases children can take Phenadryl, although it is important to consult with a doctor first to have appropriate dosage determined.

Can Phenadryl cause dizziness?

Yes, diphenhydramine can cause dizziness in some people. It is important to drink plenty of water and avoid activities that require alertness until the effects of the medication have worn off.

Can Phenadryl help with a cold?

Yes, Phenadryl can help to reduce the symptoms of a common cold such as sneezing and a runny nose.

Can Phenadryl cause constipation?

Yes, Phenadryl can cause constipation in some people. Drinking plenty of water and eating high-fiber foods can help to relieve constipation caused by diphenhydramine.

Can Phenadryl be taken with ibuprofen?

Yes, in some cases it may be safe to take diphenhydramine with ibuprofen. However, it is important to consult with a doctor to ensure it is safe to combine the medications.

Do I need a prescription for Phenadryl?

No, Phenadryl is available over-the-counter without a prescription in most cases.

Can Phenadryl be taken for an upset stomach?

No, Phenadryl is not typically used to treat symptoms of an upset stomach, and can actually make it worse. Over-the-counter medications such as antacids may be more effective for treating an upset stomach.

Is Phenadryl safe for long-term use?

Phenadryl is generally not recommended for long-term use, as chronic use can lead to dependence, tolerance, and other side effects. It is important to consult with a doctor if you are considering taking diphenhydramine for a long period of time.

Does Phenadryl have any interactions with other drugs?

Yes, Phenadryl can interact with other drugs, including some over-the-counter pain relievers, antidepressants, and muscle relaxants. It is important to consult with a doctor or pharmacist before taking any new medications.

Are there any natural alternatives to Phenadryl?

Yes, there are several natural alternatives to Phenadryl, such as lemon balm, chamomile, and lavender oil. While these are not as potent as Phenadryl, they may help to relieve symptoms of allergies and insomnia.

Can I take Phenadryl with Benadryl?

No, Benadryl is the brand name for diphenhydramine, so it is not recommended to take it with other medications containing diphenhydramine.

How much Phenadryl can I take in a day?

It is generally recommended to not take more than 300 mg of diphenhydramine per day. It is important to follow the dosing instructions on the package or as recommended by a doctor.

Does Phenadryl raise blood pressure?

Yes, in some cases diphenhydramine can raise blood pressure. People with high blood pressure should consult with a doctor before taking diphenhydramine.

Is it safe to take Phenadryl every night?

No, it is not recommended to take diphenhydramine every night, as it can lead to dependence and tolerance. Over-the-counter sleep aids may be a better option for those having difficulty sleeping.

Can Phenadryl be used to treat motion sickness?

Yes, in some cases diphenhydramine can be used to treat motion sickness.

Does Phenadryl cause weight gain?

No, diphenhydramine does not cause weight gain. However, it can increase appetite and cause issues with blood sugar levels, so people with diabetes should be especially careful when taking this medication.

Will Phenadryl help with fever?

No, diphenhydramine is not typically used to treat fever, and it can actually make symptoms worse. Over-the-counter fever-reducers such as acetaminophen or ibuprofen may be more effective.

What other medications should not be taken with Phenadryl?

Phenadryl should not be taken with other antihistamines, muscle relaxers, pain relievers, and some antidepressants. It is important to consult with a doctor before combining any medications.

Are there any over-the-counter medications that can be taken with Phenadryl?

Yes, many over-the-counter medications such as antihistamines, decongestants, and cough suppressants can be taken with diphenhydramine. It is important to consult with a doctor or pharmacist for more information.

Can Phenadryl help with poison ivy?

Yes, in some cases diphenhydramine can help to reduce the symptoms of poison ivy, such as itching and inflammation.

Can Phenadryl be taken with ibuprofen?

Yes, in some cases it may be safe to take diphenhydramine with ibuprofen. However, it is important to consult with a doctor to ensure it is safe to combine the medications.

What are the long-term effects of taking Phenadryl?

Long-term use of Phenadryl can cause dependence, tolerance, and endocrine disturbances. It is important to consult with a doctor if taking the medication longer than a few weeks.

Can Phenadryl help with itching?

Yes, Phenadryl can help to reduce itching caused by allergies or insect bites.

Does Phenadryl have any interactions with other medications or supplements?

Yes, diphenhydramine can interact with certain medications and supplements. It is important to consult with a doctor or pharmacist before taking any new medications.

What is the recommended dosage of Phenadryl?

The recommended dosage for Phenadryl varies depending on age and weight. It is important to consult with a doctor or refer to the medication label for specific instructions.

Can Phenadryl cause dry mouth?

Yes, diphenhydramine can cause dry mouth in some people. Drinking plenty of fluids and chewing sugarless gum can help to alleviate dry mouth caused by diphenhydramine.

Is it safe to drive while taking Phenadryl?

No, it is not generally recommended to drive while taking Phenadryl, as it can cause drowsiness and impair judgment. It is important to wait until fully recovered from the effects of the medication before operating a vehicle.

Can Phenadryl be used to treat a migraine?

No, Phenadryl is not typically used to treat migraine headaches. Over-the-counter medications or a prescription from a doctor may be more effective for treating migraines.

Does Phenadryl treat allergies?

Yes, Phenadryl can help to reduce allergy symptoms such as sneezing, itching, and runny nose.

Can I take Phenadryl while breastfeeding?

No, it is not recommended to take Phenadryl while breastfeeding, as it can be potentially dangerous for the baby. It is important to consult with a doctor before taking any medications while breastfeeding.

Can Phenadryl cause heart palpitations?

Yes, in some cases Phenadryl can cause heart palpitations. People with a history of heart conditions should be especially careful when taking this medication.

Does Phenadryl interact with alcohol?

Yes, the combination of diphenhydramine and alcohol can increase the risk of serious side effects. It is important to avoid drinking alcohol while taking this medication.