Hydroxyzine and Benadryl (diphenhydramine) are both widely used medications, often leading to questions about their similarities and differences. While both belong to the same class of drugs, they possess distinct characteristics that influence their primary uses and availability. Understanding these distinctions is important for safe and effective application.
How They Are Similar
Both hydroxyzine and Benadryl are first-generation antihistamines. They primarily work by blocking histamine H1 receptors in the body, which are involved in allergic reactions. This action reduces symptoms such as itching, sneezing, and watery eyes.
Both medications cause drowsiness or sedation. This sedative property results from their ability to cross the blood-brain barrier and affect the central nervous system. They are sometimes used for occasional sleep difficulties. Both can begin to work within 15 to 30 minutes after ingestion.
Key Differences
Despite their shared classification, hydroxyzine and Benadryl have notable differences in their chemical structures and approved uses. Hydroxyzine is a piperazine derivative, which contributes to its additional anti-anxiety and anti-nausea effects. In contrast, diphenhydramine (Benadryl) is an ethanolamine derivative and lacks these anxiolytic properties.
Benadryl is sold over-the-counter, while hydroxyzine requires a prescription. Hydroxyzine’s longer duration of action, which can last up to 5 days, contrasts with Benadryl’s effects, which typically subside within 4 to 6 hours. Hydroxyzine is frequently prescribed for anxiety and chronic itching, alongside its use for allergic reactions. Benadryl is primarily used for immediate allergy relief, motion sickness, and occasionally for short-term insomnia.
Both can cause drowsiness, dizziness, and dry mouth. However, hydroxyzine may have a more pronounced sedative effect. Hydroxyzine also carries a risk of more serious side effects such as irregular heart rhythms or acute generalized exanthematous pustulosis (AGEP), a rare skin condition. Benadryl is generally not recommended for children under 6 years old. Hydroxyzine has dosage recommendations for children younger than 6.
Guidance for Safe Use
Consult a healthcare professional before taking either hydroxyzine or Benadryl. This is particularly important for individuals with pre-existing medical conditions, such as heart rhythm problems, or for specific patient populations like the elderly and young children. A healthcare provider can assess potential drug interactions with other medications you may be taking, as both antihistamines can interact with central nervous system depressants like opioids, muscle relaxants, and certain antidepressants, increasing the risk of severe drowsiness or other adverse effects.
Avoid consuming alcohol while taking either medication, as alcohol can intensify their sedative effects, leading to increased drowsiness and impaired judgment. Operating heavy machinery or driving should be avoided until you understand how these medications affect you, given their potential to cause dizziness and reduced alertness. Never combine hydroxyzine and Benadryl without medical advice, as this can increase the risk and severity of side effects.