Diphenhydramine, commonly known as Benadryl, is an over-the-counter antihistamine. It alleviates allergy symptoms like sneezing, runny nose, and itchy eyes or throat. This medication also addresses cold symptoms and serves as a short-term sleep aid due to its sedative properties. Understanding the potential effects of accidentally taking more than the recommended dose is important.
Understanding Benadryl’s Usual Effects
At recommended doses, Benadryl primarily blocks histamine H1 receptors, reducing allergy symptoms like itching, sneezing, and runny nose. It also readily crosses the blood-brain barrier, affecting the central nervous system, which contributes to its well-known side effect of drowsiness.
Beyond its antihistamine and sedative effects, diphenhydramine also possesses anticholinergic properties. These can help relieve nausea, vomiting, and dizziness, making it useful for motion sickness. Typical side effects at standard doses include dry mouth, blurred vision, dizziness, and mild constipation. These effects generally subside within four to six hours.
Recognizing Signs of Too Much Benadryl
Taking four Benadryl tablets (typically 100 mg if each is 25 mg) can significantly amplify its intended and side effects. The recommended adult dose is 25-50 mg every four to six hours, with a maximum daily intake of 300 mg. Exceeding this dose can intensify the medication’s impact on the central nervous system and other bodily functions.
Symptoms of exceeding the recommended dose include severe drowsiness, pronounced dizziness, and difficulty with balance or coordination. Dry mouth, blurred vision, and difficulty urinating can become more noticeable due to amplified anticholinergic effects. More concerning signs of overdose include confusion, disorientation, agitation, and restlessness.
Higher doses can lead to severe neurological effects such as hallucinations, muscle twitching, rapid heartbeat (tachycardia), and irregular heart rhythms. Severe overdose may result in seizures or even a coma. The severity of these symptoms can vary based on individual factors like age, medical conditions, and other medications.
When to Get Medical Help
Seek immediate medical attention if severe symptoms such as seizures, severe confusion, or hallucinations develop from an accidental Benadryl overdose. Difficulty breathing, unresponsiveness, or a very rapid or irregular heartbeat are also signals for urgent medical evaluation. These serious effects indicate a significant reaction.
For any suspected overdose, contacting a poison control center is a recommended first step. In the U.S., the national Poison Help hotline (1-800-222-1222) provides expert guidance. They can assess the situation and advise on necessary care based on reported symptoms and medication taken. Do not wait for symptoms to worsen.
Safe Medication Practices
Preventing accidental medication overdoses involves careful habits. Always read the label and dosage instructions thoroughly before taking any medication. Understand the recommended dose, frequency, and specific instructions to ensure correct use. Use appropriate measuring devices, such as dosing cups or spoons, for accuracy, particularly for children’s doses.
Avoid simultaneous use of multiple medications containing the same active ingredient. Many cold and flu remedies include diphenhydramine, and taking these alongside Benadryl can lead to an unintended overdose.
Store medications securely, out of reach of children and pets, to prevent accidental ingestion. A locked cabinet or high shelf is ideal. Keep medications in their original containers for efficacy and information. Regularly review and dispose of expired or unused medications safely through drug take-back programs or other methods.