Hydroxyzine is considered an antagonist drug of a complex molecule called histamine, which has key functions in blood circulation, allergic reactions and even participates directly with the immune system.
In this article, we will learn more about the key functions of hydroxyzine, including its composition, properties, adverse effects, and contraindications.
What is hydroxyzine?
Hydroxyzine is a generic drug and an active ingredient with antihistamine properties, the mechanism of action of which is to inhibit the effects of the chemical histamine, counteract allergic reactions and certain central nervous system (CNS) functions.
It should be noted that this medication is used by oral administration, since it comes in the form of tablets of between 25 mg and 30 mg. On the other hand, the doses of hydroxyzine may depend on the patient’s case , although capsules of between 50 to 100 mg per day are started in the first weeks.
Note: One study mentions that: “ Hydroxyzine is an H1 antihistamine drug and also an anxiolytic agent in the symptomatic treatment of pruritus and urticaria” . (1)
What is hydroxyzine used for?
This drug has essential functions for the nervous system, the cardiovascular system and can balance the immune defenses , always with moderate use. Among those functions are the following:
1. Anxiety and tension
Anxiety is a normal reaction of the body to danger, although it causes an increase in psychophysiological activity in the nervous system. For these cases, a maximum dose of hydroxyzine of between 50 to 100 mg per day is recommended, in the mildest states.
To highlight: It is recommended to take this medicine to balance the heartbeat , since anxiety can cause an increase in blood pressure (tachycardia) that, although temporary, can negatively affect older adults.
2. Allergic reactions
Allergic reactions are diverse and many can be mild or severe (which happens in hypersensitive patients), but in itself it is a reaction of the immune system to a very specific substance in adults and children.
You should know: It is recommended that hydroxyzine should be used in cases of skin rashes such as pruritus (tingling on the skin), urticaria (rashes due to the release of histamine) or nasal congestion, which requires the use of a 25mg capsule every night to be properly absorbed.
3. Medication prior to anesthesia
At this point it is called prior anesthetic medication, in the case of the use of drugs that seek to relieve anxiety, stress and balance breathing , which is necessary to also calm the nerves before an important operation.
Note: The drug hydroxyzine is recommended for these cases, since it balances the sympathetic hyperactivity of the nervous system , reduces anxiety, but it is also because it has a very positive sedation effect, at the time of local anesthesia.
Hydroxyzine Side Effects
Due to all of the above, it is almost impossible for the drug hydroxyzine to be free of side reactions, which should occur, the use of this drug should be discontinued and a report to your doctor should be made if the reactions continue. The effects that should be known are the following:
- Fatigue.
- Drowsiness (increased desire for sleep).
- Headache (headache) and dry mouth.
Important: A study mentions that: ” Involuntary motor activity, including tremors and convulsions , has been reported infrequently with hydroxyzine , generally with dosages considerably higher than those recommended.” (two)
Contraindications of hydroxyzine
Finally, for safety reasons, this drug is contraindicated for a certain number of people and patients , especially those who suffer from the following conditions:
- Hypersensitivity or allergic reaction to hydroxyzine.
- Patients under consumption of drugs that depress the nervous system.
- Cardiovascular diseases or disorders.
- Pregnancy and lactation.
To highlight: One study mentions that: “ The use of hydroxyzine is contraindicated in patients with prolongation of the QT interval (acquired or congenital) and in patients with risk factors for prolongation of the QT interval” . (3)
Key Findings
- Hydroxyzine is a generic medication with antihistamine properties .
- It is used to relieve symptoms of anxiety, tension, allergic reactions and also as a pre-anesthesia medication.
- It is recommended to use under prescription and medical supervision , to reduce adverse effects such as headache, fatigue and drowsiness.
- It is contraindicated for patients allergic to its composition and those with chronic heart problems.

University Professional in the area of Human Resources, Postgraduate in Occupational Health and Hygiene of the Work Environment, 14 years of experience in the area of health. Interested in topics of Psychology, Occupational Health, and General Medicine.