Antihistamine vs. Hydroxyzine

What's the Difference?

Antihistamines and Hydroxyzine are both medications commonly used to treat allergies and allergic reactions. However, there are some key differences between the two. Antihistamines are a class of drugs that block the action of histamine, a chemical in the body that causes allergy symptoms. They are available over-the-counter and come in various forms such as pills, liquids, and nasal sprays. On the other hand, Hydroxyzine is a prescription medication that is also used to treat allergies, but it is also used to treat anxiety and itching. It works by blocking histamine receptors in the brain, leading to sedation and relaxation. Overall, while both medications are effective in treating allergies, Hydroxyzine has additional uses and may cause more sedation than traditional antihistamines.


UsageTreats allergiesTreats anxiety and itching
Brand namesBenadryl, Claritin, ZyrtecAtarax, Vistaril
Side effectsDrowsiness, dry mouthDizziness, drowsiness
Prescription requiredSomeYes

Further Detail


Antihistamines and hydroxyzine are both medications commonly used to treat allergic reactions and symptoms such as itching, hives, and runny nose. While they belong to the same class of drugs, there are some key differences between the two that patients should be aware of when considering which medication to use.

Mechanism of Action

Antihistamines work by blocking the action of histamine, a chemical in the body that is released during an allergic reaction. By blocking histamine, antihistamines can help alleviate symptoms such as itching, sneezing, and watery eyes. Hydroxyzine, on the other hand, is a first-generation antihistamine that also works by blocking histamine receptors in the body. However, hydroxyzine has additional sedative properties that make it useful for treating anxiety and insomnia.

Side Effects

Both antihistamines and hydroxyzine can cause side effects such as drowsiness, dry mouth, and dizziness. However, hydroxyzine is more likely to cause sedation compared to newer, second-generation antihistamines. This sedative effect can be beneficial for patients who have trouble sleeping or who are experiencing anxiety, but it can also make it unsafe to drive or operate heavy machinery while taking hydroxyzine.

Duration of Action

One key difference between antihistamines and hydroxyzine is the duration of action. Antihistamines such as loratadine and cetirizine are known for their long-lasting effects, with some formulations providing relief for up to 24 hours. In contrast, hydroxyzine has a shorter duration of action and may need to be taken multiple times a day to maintain its effectiveness.


Antihistamines are commonly used to treat allergic reactions, hay fever, and hives. They can also be used to relieve symptoms of the common cold, such as sneezing and runny nose. Hydroxyzine, on the other hand, is often prescribed for anxiety, itching, and as a sedative for preoperative anxiety. It is also sometimes used off-label to treat nausea and vomiting.

Drug Interactions

Both antihistamines and hydroxyzine can interact with other medications, so it is important to consult with a healthcare provider before starting treatment. Antihistamines may interact with drugs that cause drowsiness, such as benzodiazepines and opioids. Hydroxyzine, on the other hand, can enhance the sedative effects of other central nervous system depressants, increasing the risk of side effects such as drowsiness and dizziness.


While both antihistamines and hydroxyzine are effective medications for treating allergic reactions and symptoms, they have different mechanisms of action, side effects, and indications. Patients should work closely with their healthcare provider to determine which medication is best suited for their individual needs and medical history. By understanding the differences between these two medications, patients can make informed decisions about their treatment options.

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