Diphenhydramine is a widely available over-the-counter antihistamine used to alleviate symptoms associated with seasonal allergies, other allergic reactions, and the common cold. This medication is also effective in treating itchy skin, hives, and various other related conditions.
Its primary benefit lies in its ability to significantly reduce itchy skin caused by hives, often making it a preferred initial treatment for this condition. It also helps in managing symptoms of certain seasonal allergies.
What is Diphenhydramine?
Diphenhydramine is a first-generation antihistamine and anticholinergic compound. It belongs to the ethanolamine class of medications and interacts with histamine receptors in the body.
It has a chemical structure that enables it to cross the blood-brain barrier and exert an influence on the central nervous system. Its molecular formula is C17H21NO .
This medication is commonly found as Diphenhydramine 25 mg tablets, capsules, liquid-filled capsules, dissolving strips, and liquids. It is also known by its Diphenhydramine brand name such as Benadryl.
What Are the Uses of Diphenhydramine?
Diphenhydramine is an antihistamine that reduces the effects of the body's natural chemical histamine, which can cause symptoms like sneezing, itching, watery eyes, and a runny nose. Diphenhydramine uses extend beyond just allergies.
Diphenhydramine is also used for treating motion sickness, to induce sleep, and for managing some symptoms associated with Parkinson's disease.
How Does Diphenhydramine Work?
Diphenhydramine hydrochloride primarily works by blocking the effects of histamine at the H1 (histamine 1) receptors in the body. Histamine is a substance released during allergic reactions, causing symptoms like itching, sneezing, and a runny nose.
By blocking these receptors, Diphenhydramine helps to alleviate these allergic responses. It also has other effects, including some action on cholinergic receptors, which contributes to its sedative properties.
How to Take Diphenhydramine
Diphenhydramine is available in various oral forms, including:
Tablets
Capsules (including liquid-filled)
Oral liquids
Dissolving strips
General Guidelines:
For allergies, cold, and cough symptoms: Take every 4 to 6 hours as needed. Do not exceed the recommended dose.
For motion sickness: Take 30 minutes before travel. You may also take it before meals and bedtime if needed.
For insomnia (sleep aid): Take 30 minutes before bedtime to help induce sleep.
Important Safety Tips:
Always read labels carefully if using multiple over-the-counter (OTC) products.
Many cold and cough medications contain diphenhydramine, which can lead to accidental overdose if duplicated.
Use with caution in children, and do not combine medications without medical advice.
Diphenhydramine Dosage
Maximum Daily Dose (adults): Do not exceed 300 mg in 24 hours.
Use
Age Group
Typical Dose
Frequency
Allergies, Cough
Adults and ≥12 years
25-50 mg
Every 4-6 hours (Max 300 mg/day)
Children 6-11 years
12.5-25 mg
Every 4-6 hours
Children <6 years
Doctor's supervision only
Motion Sickness
Adults
25-50 mg
30 min before travel; then before meals/bedtime
Insomnia
Adults and ≥12 years
50 mg
30 min before bedtime
Important Notes:
Always follow package instructions or your doctor's advice.
For children under 6 years old, diphenhydramine should only be used under medical supervision.
Do not combine with other medications that contain diphenhydramine (including nighttime pain relievers or cold meds).
What Should I Do If I Miss a Dose of Diphenhydramine?
Missing one or two doses of Diphenhydramine typically won't have a significant effect on your body. The skipped dose usually causes no problem.
However, for some medications, consistent timing is crucial for effectiveness. If you miss a dose, follow your doctor's advice to take the prescribed medicine as soon as possible.
What happens if an Overdose?
An overdose of a drug can be accidental. If you have taken more than the prescribed Diphenhydramine tablet, there is a chance of experiencing harmful effects on your body's functions. An overdose of medicine can lead to a medical emergency.
Symptoms of overdose
Common symptoms of Diphenhydramine overdose include excessive sleepiness, dry mouth, flushing, nausea, vomiting, and a fast heartbeat. More serious symptoms can include confusion, hallucinations, delirium, seizures, coma, and in rare cases, death.
What to avoid
Avoid taking more than the recommended dosage of Diphenhydramine. Do not participate in social media challenges that encourage taking excessive amounts of medication, as these can lead to serious health consequences.
Always read labels carefully, especially when using multiple over-the-counter cough and cold products, as they may contain the same active ingredients, leading to accidental overdose.
Get a second opinion from trusted experts and makeconfident, informed decisions.
Diphenhydramine side effects can vary, but many people who use this medicine do not experience any side effects. A doctor will advise you to take the medicine after considering your problems and the benefits, which are typically greater than the potential side effects.
Common side effects
Some of the common side effects of Diphenhydramine are:
If you experience any of these severe symptoms, please contact your doctor immediately for further assistance. In any case, if you experience any reaction to Diphenhydramine, try to avoid it.
A doctor advised you to take the medicines after seeing your problems and the benefits of this medicine, which are greater than the side effects. The majority of the people who use this medicine don't show any side effects. Get medical help immediately if you get any serious Diphenhydramine side effects.
Precautions and Warnings
Before taking Diphenhydramine tablets, it is important to discuss any allergies you have to the medication or any other substances with your doctor. The product may contain inactive ingredients that could cause allergic reactions or other serious problems.
Who should avoid this medicine?
Generally, Diphenhydramine should not be used in older adults, except for serious allergic reactions, as it may not be as safe or effective as other medications for their condition.
Nonprescription cough and cold combination products containing Diphenhydramine should not be given to children younger than 4 years of age due to the risk of serious side effects or death.
The FDA warns against giving any cold or cough medicine containing an antihistamine to a child under the age of 2 due to potential serious side effects like rapid heart rate and convulsions.
Conditions where caution is needed
Before using the medication, talk to your doctor if you have any of the following medical histories:
Are There Any Age Restrictions for Using Diphenhydramine?
Yes, there are age restrictions for using Diphenhydramine. For allergies, it is generally not recommended for children under 1 year of age. For cold symptoms, it is not recommended at any age due to a lack of proven benefits and should be avoided in children under 4 years old.
The FDA advises against giving any cold or cough medicine containing an antihistamine to children under 2 years old due to the risk of serious side effects.
For children aged 4 to 11, use caution and follow package directions carefully. In older adults (65 years or older), discuss the risks and benefits with your doctor, as these medications may not be as safe or effective as others.
Alcohol or food interactions
Diphenhydramine and alcohol are both central nervous system (CNS) depressants. Taking them together can worsen side effects such as drowsiness, dizziness, confusion, and headache. It is recommended to avoid alcohol while taking Diphenhydramine. There are no significant food interactions reported for Diphenhydramine.
Possible Interactions with Other Medications (Drug Interactions)
Drug interactions can change how your medicines work or increase your risk of serious side effects. Keep a list of all the products you use, including prescription and over-the-counter medications, and share it with your doctor and pharmacist.
Overview of how this medicine may interact with other drugs
Talk to your doctor if you are taking other products that can cause drowsiness, such as opioid pain relievers or cough pain relievers, and substances like alcohol and marijuana. Combining Diphenhydramine with other CNS depressants can lead to excessive sedation and impaired cognitive and physical tasks.
Possible impact when combined with supplements, herbal products
Always inform your doctor and pharmacist about any supplements or herbal products you are taking, as these can also interact with Diphenhydramine and potentially alter its effects or increase the risk of side effects.
How Should Diphenhydramine Be Stored?
Diphenhydramine should be stored properly to maintain its effectiveness and safety. Direct exposure to heat, air, and light may damage your medicine.
Recommended Storage Temperature for Diphenhydramine
Oral Diphenhydramine products, including Diphenhydramine tablet and Diphenhydramine syrup, should be stored at room temperature, ideally between 68°F and 77°F (20°C and 25°C). They can tolerate brief exposures to temperatures between 59°F and 86°F (15°C and 30°C), such as during transport.
What Happens If Diphenhydramine Is Not Stored Properly?
If Diphenhydramine is not stored correctly, it may lose its effectiveness over time. Exposure to extreme heat, air, or light can cause degradation of the medication. It is crucial to keep the container tightly closed and away from excess heat and moisture (avoid placing it in the bathroom).
Keep away from children, sunlight, or moisture.
Always keep Diphenhydramine and all other medications out of the sight and reach of children and pets. Many containers are not child-resistant, so it's essential to store medicines in a secure, locked location that's out of their reach. Protect the medication from light.
Diphenhydramine Vs Cetirizine
Diphenhydramine
Cetirizine
Diphenhydramine is an over-the-counter antihistamine used to relieve symptoms of allergies, hay fever, and the common cold.
Cetirizine tablets are antihistamines used to relieve allergy symptoms such as watery eyes, runny nose, sneezing, hives, and itching.
It works by blocking the effects of histamine, a chemical responsible for allergic symptoms like sneezing, itching, and runny nose.
Cetirizine provides relief from allergic reactions but does not prevent hives from occurring.
Yes, diphenhydramine is used to relieve cough, especially when it's caused by throat irritation or allergies. It works as an antihistamine and cough suppressant, helping reduce coughing, sneezing, and runny nose.
Serious side effects of diphenhydramine include decreased memory, impaired thinking, dementia, irregular heartbeat, and seizures.
Diphenhydramine can make you feel sleepy, as it may cause serious side effects. Consult your doctor if you experience significant side effects.
Diphenhydramine is available in forms like tablets, capsules, liquid-filled capsules, dissolving strips, and liquid, which can be taken orally. It can be taken before sleep to help improve sleep quality.
Benadryl cough medicine can be used to relieve cold symptoms such as cough and congestion. However, always consult a healthcare professional before using it for off-label purposes.
Diphenhydramine can be used in children, but the dosage and formulation, such as syrup or tablets, must be appropriate for their age. Always follow the pediatrician’s advice and the medication label instructions.
Diphenhydramine HCL works by blocking histamine, a substance in the body that triggers allergic symptoms, helping to reduce itching, swelling, and other allergy-related symptoms.
Some medications may interact with diphenhydramine, so it’s important to inform your doctor about all medications you’re taking, including over-the-counter drugs and supplements.
There is no difference; diphenhydramine hydrochloride is the full chemical name for diphenhydramine, commonly referred to as diphenhydramine HCL.
Diphenhydramine Oral Solution BP 12.5 mg/5 mL is used to treat allergy symptoms, hay fever, the common cold, and dry cough. It helps relieve runny nose, sneezing, itchy or watery eyes, itchy throat, and cough due to minor throat irritation.
Disclaimer: The information provided is accurate and up-to-date to the best of our knowledge. However, it should not be considered a substitute for medical advice or consultation. We do not guarantee its completeness or accuracy. The absence of specific warnings does not mean a medicine is safe for all users. We are not responsible for any outcomes based on this information and strongly recommend consulting a doctor for any medical concerns or questions.
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