Diphenhydramine
Perennial Allergic Rhinitis, Nausea ... show more
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Drug Status
Government Approvals
US(FDA), UK(BNF)
WHO Essential Medicine
NO
Known Teratogen
NO
Pharmaceutical Class
Histamine-1 Receptor Antagonist
Controlled Drug Substance
No
Diphenhydramine
Summary
Diphenhydramine is used to manage symptoms of allergies like runny nose, sneezing, and itchy eyes. It's also used to prevent and treat motion sickness, manage insomnia, and control abnormal movements in early-stage Parkinson's disease.
Diphenhydramine works by blocking the action of histamine, a substance in your body that triggers allergy symptoms. It also affects the central nervous system, providing a sedative effect that can help with sleep and reduce motion sickness.
For adults, the usual dose is 25 to 50 mg every 4 to 6 hours, not exceeding 300 mg per day. For children aged 6 to 11 years, the dose is typically 12.5 to 25 mg every 4 to 6 hours, not exceeding 150 mg per day. Children under 6 years should not use it unless directed by a doctor.
Common side effects include drowsiness, dizziness, fatigue, dry mouth, and nausea. More serious effects, though rare, can include vision problems and difficulty urinating.
Avoid using Diphenhydramine in children under 4 years and with caution in older adults. Don't use it if you have conditions like glaucoma, enlarged prostate, or breathing problems. Avoid alcohol as it can increase drowsiness. Consult a doctor if you have any health concerns before using this medication.
Indications and Purpose
How does Diphenhydramine work?
Diphenhydramine works by blocking the action of histamine, a chemical in the body that triggers allergy symptoms. It also affects the central nervous system, providing a sedative effect that can help with sleep and reduce motion sickness. This dual action makes it effective for multiple conditions.
Is Diphenhydramine effective?
Diphenhydramine is an antihistamine that effectively relieves symptoms of allergies, such as runny nose, sneezing, and itchy eyes, by blocking histamine action in the body. It is also used for motion sickness, insomnia, and cough relief. Its effectiveness is well-documented in clinical practice, though individual responses may vary.
What is Diphenhydramine?
Diphenhydramine is an antihistamine used to relieve allergy symptoms, prevent motion sickness, and treat insomnia. It works by blocking histamine, a substance in the body that causes allergic reactions. It also has sedative properties, making it effective for sleep aid. However, it should be used with caution due to potential side effects like drowsiness.
Directions for Use
For how long do I take Diphenhydramine?
Diphenhydramine is typically used on an as-needed basis for short-term relief of symptoms. For sleep disturbances, it should not be used continuously for more than two weeks without consulting a doctor. Always follow the guidance of a healthcare professional regarding duration of use.
How do I take Diphenhydramine?
Diphenhydramine can be taken with or without food. If it causes stomach upset, taking it with food may help. There are no specific food restrictions, but avoid alcohol as it can increase drowsiness. Always follow the dosage instructions on the label or as prescribed by your doctor.
How long does it take for Diphenhydramine to start working?
Diphenhydramine typically starts working within 30 minutes to an hour after taking it. Its effects can last for 4 to 6 hours. For sleep aid, it is recommended to take it 30 minutes before bedtime to allow it to take effect.
How should I store Diphenhydramine?
Store diphenhydramine in its original container, tightly closed, at room temperature away from excess heat and moisture. Keep it out of reach of children and pets. Do not store it in the bathroom. Proper storage ensures the medication remains effective and safe to use.
What is the usual dose of Diphenhydramine?
For adults, the usual dose of diphenhydramine is 25 to 50 mg every 4 to 6 hours, not exceeding 300 mg per day. For children aged 6 to 11 years, the dose is typically 12.5 to 25 mg every 4 to 6 hours, not exceeding 150 mg per day. Children under 6 years should not use diphenhydramine unless directed by a doctor.
Warnings and Precautions
Can Diphenhydramine be taken safely while breastfeeding?
Diphenhydramine is present in breast milk, and its effects on a nursing infant are unknown. It is generally not recommended for breastfeeding mothers unless advised by a doctor. If used, monitor the infant for any adverse effects and consult a healthcare provider for guidance.
Can Diphenhydramine be taken safely while pregnant?
Diphenhydramine should be used during pregnancy only if clearly needed, as it crosses the placenta. There is limited evidence on its safety, and potential risks to the fetus are unknown. Pregnant women should consult their doctor before using this medication to weigh potential benefits and risks.
Can I take Diphenhydramine with other prescription drugs?
Diphenhydramine can interact with other medications that cause drowsiness, such as sedatives, tranquilizers, and certain antidepressants. It may also interact with MAO inhibitors, increasing side effects. Always inform your doctor about all medications you are taking to avoid potential interactions.
Is Diphenhydramine safe for the elderly?
Diphenhydramine is generally not recommended for older adults due to increased sensitivity to its side effects, such as confusion, dizziness, and sedation. These can increase the risk of falls and other accidents. If necessary, it should be used under close medical supervision, and alternative treatments should be considered.
Is it safe to drink alcohol while taking Diphenhydramine?
Drinking alcohol while taking diphenhydramine can increase drowsiness and dizziness, making it unsafe to drive or operate machinery. Alcohol can enhance the sedative effects of diphenhydramine, leading to increased risk of accidents or injuries. It is advised to avoid alcohol while using this medication.
Is it safe to exercise while taking Diphenhydramine?
Diphenhydramine can cause drowsiness, dizziness, and muscle weakness, which may limit physical performance and exercise capacity. If you experience these side effects, it is advisable to avoid strenuous activities and consult your doctor for guidance.
Who should avoid taking Diphenhydramine?
Important warnings for diphenhydramine include avoiding use in children under 4 years, caution in older adults, and avoiding alcohol due to increased drowsiness. It should not be used if you have certain medical conditions like glaucoma, enlarged prostate, or breathing problems. Always consult a doctor if you have any health concerns before using this medication.
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