Benadryl, scientifically known as diphenhydramine, is a widely accessible over-the-counter antihistamine. People commonly use it to alleviate various symptoms, including those associated with seasonal allergies, such as sneezing, runny nose, itchy throat, and watery eyes. It also offers relief from common cold symptoms and can serve as a temporary sleep aid due to its sedative properties.
Recommended Dosage and Frequency
For adults, the typical oral dosage of Benadryl is 25 to 50 milligrams (mg) per dose, taken every four to six hours as needed. Do not exceed 300 mg within a 24-hour period. Benadryl is available in various forms, including tablets, capsules, chewable tablets, and liquid solutions. Use the provided dosing cup, spoon, or oral syringe for liquid forms to ensure accurate measurement.
The effects of Benadryl typically manifest within 15 to 30 minutes after oral administration, with peak effectiveness occurring between one and two hours. Effects typically last four to six hours, aligning with the recommended dosing frequency. Age, metabolism, and dosage influence how long it remains active.
Important Considerations and Precautions
Common side effects include drowsiness, dry mouth, dry nose, dry throat, blurred vision, dizziness, and constipation. More serious side effects include confusion, excitability (especially in children), difficulty urinating, a fast or irregular heartbeat, muscle weakness, or impaired coordination.
Benadryl interacts with many medications and substances, increasing adverse effects. Avoid combining it with alcohol, sedatives, tranquilizers, or other sleep aids, as this significantly enhances drowsiness, dizziness, and confusion. Do not take Benadryl with other antihistamines, including those in combination cold and allergy products, to avoid excessive diphenhydramine. Certain antidepressants, like tricyclic antidepressants and trazodone, can also increase sedation.
Caution is advised for individuals with pre-existing health conditions. Conditions like glaucoma, enlarged prostate, asthma, emphysema, chronic bronchitis, heart disease, or high blood pressure may worsen. Liver or kidney disease can increase side effects by affecting drug processing.
Do not operate machinery or drive after taking Benadryl due to drowsiness and impaired reactions. Prolonged use can lead to tolerance, especially to sedative effects, making it less effective. Therefore, long-term use, particularly as a sleep aid, is not recommended; limit usage to less than two weeks.
When to Consult a Healthcare Professional
Consult a healthcare professional if symptoms persist or worsen after seven days. Contact a healthcare professional immediately for severe or unusual side effects like extreme drowsiness, hallucinations, difficulty urinating, irregular heartbeat, or seizures. Seek immediate emergency medical attention for signs of a severe allergic reaction, including sudden swelling of the lips, mouth, throat, or tongue, or difficulty breathing.
For suspected overdose (extreme sleepiness, confusion, dilated pupils, fast heartbeat, convulsions), contact a poison control center or emergency services promptly. Before use, consult a doctor or pharmacist if uncertain about drug interactions, have underlying health conditions, or need dosage clarification. Dosage and considerations for children and older adults (65+) differ significantly, making professional guidance important for these groups.