What are the symptoms of taking too much Benadryl? What should you do if you suspect an antihistamine overdose. Find out the answers here.

Antihistamine Overdose: A Dangerous Scenario

Antihistamines are a class of medication used to alleviate allergy symptoms like sneezing, runny nose, and itching. While these drugs are generally safe when taken as directed, taking too much can lead to an overdose and serious adverse effects. An antihistamine overdose can occur when a person takes 3 to 5 times the normal recommended dose, which can happen accidentally or intentionally. Regardless of the reason, an antihistamine overdose requires immediate medical attention.

Symptoms of Antihistamine Overdose

The symptoms of an antihistamine overdose can vary depending on factors like the type and amount of antihistamine taken, the person’s age and size, and any underlying health conditions. In children, common symptoms may include excitement, jitteriness, a fast heart rate, irritability, hallucinations, and seizures. As the overdose progresses, the child may experience drowsiness, slowed breathing, and even coma.

In adults, an antihistamine overdose can cause fever, flushing, dilated pupils, a fast heart rate, low blood pressure, coma, and the inability to completely empty the bladder. Second-generation antihistamines like Claritin and Allegra tend to have less serious effects in an overdose, but any antihistamine overdose can be dangerous and should be treated promptly.

What to Do in an Antihistamine Overdose

If you suspect someone has overdosed on an antihistamine, the first step is to call the American Association of Poison Control Centers (AAPCC) at 1-800-222-1222. This 24-hour, toll-free hotline can provide guidance on the appropriate course of action. If the person is experiencing severe symptoms like trouble breathing, a rapid or slow heart rate, seizures, or loss of consciousness, call 911 or go to the nearest emergency room immediately.

Diagnosing an antihistamine overdose may involve a discussion about all medications the person is taking, not just the antihistamine, as other drugs can also contain antihistamine components. A physical exam may be necessary to check for signs like drowsiness, irritability, blurred vision, or abnormal vital signs.

Preventing Antihistamine Overdoses

To avoid an antihistamine overdose, it’s crucial to follow the dosage instructions on the medication’s packaging or as advised by a healthcare provider. Antihistamines should be kept out of reach of children, and adults should be cautious when taking antihistamines in combination with other medications, as this can increase the risk of an overdose.

While antihistamines are generally considered safe when used as directed, it’s important to remember that they are still a class of drugs, and taking too much can be dangerous. If you have any concerns or questions about antihistamine use, be sure to consult with a healthcare professional.

The Dangers of First-Generation Antihistamines

According to a position statement from the Canadian Society of Allergy and Clinical Immunology (CSACI), first-generation antihistamines like Benadryl (diphenhydramine) can have “intolerable and potentially life-threatening adverse effects” in large doses. These older antihistamines, which also include chlorpheniramine and brompheniramine, can have a more significant impact on the central nervous system, leading to issues like jitteriness and drowsiness.

In contrast, second-generation antihistamines like Claritin (loratadine), Zyrtec (cetirizine), and Allegra (fexofenadine) are generally less likely to cause these types of severe side effects, even in an overdose. However, it’s important to note that any antihistamine overdose can be dangerous and should be treated promptly.

Antihistamine Overdose in Children and the Elderly

Children and older adults are at a higher risk of experiencing an antihistamine overdose compared to healthy adults. Studies have shown that children can develop serious complications like heart problems, seizures, and even death from an antihistamine overdose. The most common reactions in children are milder, such as rashes, sleepiness, and headaches.

While second-generation antihistamines are generally less likely to cause toxicity in children than first-generation ones, a study found that even these newer antihistamines can still lead to dangerous symptoms in the event of an overdose. Therefore, it’s crucial for parents and caregivers to follow dosage guidelines carefully and keep all medications, including antihistamines, out of the reach of children.

The Bottom Line

Antihistamines are a common and generally safe medication when taken as directed, but an overdose can be a serious and potentially life-threatening situation. Knowing the symptoms of an antihistamine overdose and what to do in such an event can help ensure prompt and appropriate medical treatment, which is crucial for a positive outcome. By exercising caution and following dosage instructions, individuals can help prevent accidental antihistamine overdoses and protect themselves and their loved ones.