Hydroxyzine Uses, Dosage, Side Effects, Food Interaction and all others data.

Hydroxyzine, a piperazine derivative, blocks histamine H1-receptors on effector cells of the GI tract, blood vessels and resp. It is a sedating antihistamine w/ antimuscarinic and significant sedative properties. It also possesses skeletal muscle relaxing, bronchodilator, antiemetic and analgesic properties.

Hydroxyzine blocks the activity of histamine to relieve allergic symptoms such as pruritus. Activity at off-targets also allows for its use as a sedative anxiolytic and an antiemetic in certain disease states.

Hydroxyzine is relatively fast-acting, with an onset of effect that occurs between 15 and 60 minutes and a duration of action between 4-6 hours. Hydroxyzine may potentiate the effects of central nervous system (CNS) depressants following general anesthesia - patients maintained on hydroxyzine should receive reduced doses of any CNS depressants required. Hydroxyzine is reported to prolong the QT/QTc interval based on postmarketing reports of rare events of Torsade de Pointes, cardiac arrest, and sudden death, and should be used with caution in patients with an increased baseline risk for QTc prolongation.

Trade Name Hydroxyzine
Availability Prescription only
Generic Hydroxyzine
Hydroxyzine Other Names Hidroxizina, Hychotine, Hydroksyzyny, Hydroxine, Hydroxizine, Hydroxizinum, Hydroxycine, Hydroxyzin, Hydroxyzine, Hydroxyzinum, Idrossizina
Related Drugs Buprenex, aspirin, acetaminophen, tramadol, trazodone, escitalopram, alprazolam, duloxetine, Lexapro, naproxen
Type Injection, Solution, Oral Solution, Tablet, Film Coated, Intramuscular, Capsule
Formula C21H27ClN2O2
Weight Average: 374.904
Monoisotopic: 374.176105825
Protein binding

Hydroxyzine has been shown to bind to human albumin in vitro, but the extent of protein binding in plasma has not been evaluated.

Groups Approved
Therapeutic Class Sedating Anti-histamine
Available Country Canada, United States
Last Updated: September 19, 2023 at 7:00 am


For symptomatic relief of anxiety and tension associated with psychoneurosis and as an adjunct in organic disease states in which anxiety is manifested. Useful in the management of pruritus due to allergic conditions such as chronic urticaria and atopic and contact dermatoses, and in histamine-mediated pruritus.

As a sedative when used as premedication and following general anesthesia, hydroxyzine may potentiate meperidine and barbiturates, so their use in pre-anesthetic adjunctive therapy should be modified on an individual basis. Atropine and other belladonna alkaloids are not affected by the drug. Hydroxyzine is not known to interfere with the action of digitalis in any way and it may be used concurrently with this agent.

The effectiveness of hydroxyzine as an antianxiety agent for long term use, that is more than 4 months, has not been assessed by systematic clinical studies. The physician should reassess periodically the usefulness of the drug for the individual patient.

Hydroxyzine is also used to associated treatment for these conditions: Anxiety, Nausea and vomiting, Pruritus

How Hydroxyzine works

The H1 histamine receptor is responsible for mediating hypersensitivity and allergic reactions. Exposure to an allergen results in degranulation of mast cells and basophils, which then release histamine and other inflammatory mediators. Histamine binds to, and activates, H1 receptors, which results in the further release of pro-inflammatory cytokines, such as interleukins, from basophils and mast cells. These downstream effects of histamine binding are responsible for a wide variety of allergic symptoms, such as pruritus, rhinorrhea, and watery eyes.

Hydroxyzine is a potent inverse agonist of histamine H1-receptors - inverse agonists are agents that are considered to have a "negative efficacy", so rather than simply blocking activity at a receptor they actively dampen its activity. Inverse agonism at these receptors is responsible for hydroxyzine's efficacy in the treatment of histaminic edema, flare, and pruritus.

Hydroxyzine is not a cortical depressant, so its sedative properties likely occur at the subcortical level of the CNS. These sedative properties allow activity as an anxiolytic. Antiemetic efficacy is likely secondary to activity at off-targets.


Hydroxyzine dosage

For symptomatic relief of anxiety and tension associated with psychoneurosis and as an adjunct in organic disease states in which anxiety is manifested: 

  • Adults: 50-100 mg q.i.d.
  • Children under 6 years: 50 mg daily in divided doses
  • Over 6 years: 50-100 mg daily in divided doses

For use in the management of pruritus due to allergic conditions such as chronic urticaria and atopic and contact dermatoses, and in histamine-mediated pruritus: 

  • Adults: 25 mg t.i.d. or q.i.d.
  • Children under 6 years: 50 mg daily in divided doses
  • Over 6 years: 50-100 mg daily in divided doses

As a sedative when used as a premedication and following general anesthesia: 

  • Adults: 50-100 mg
  • Children: 0.6 mg/kg of body weight

When treatment is initiated by the intramuscular route of administration, subsequent doses may be administered orally. As with all medications, the dosage should be adjusted according to the patient's response to therapy.

May be taken with or without food.

Side Effects

Side effects reported with the administration of hydroxyzine hydrochloride are usually mild and transitory in nature.

Anticholinergic: Dry mouth.

Central Nervous System: Drowsiness is usually transitory and may disappear in a few days of continued therapy or upon reduction of the dose. Involuntary motor activity including rare instances of tremor and convulsions have been reported, usually with doses considerably higher than those recommended. Clinically significant respiratory depression has not been reported at recommended doses.


The oral LD50 is 840 mg/kg in rats and 400 mg/kg in mice.

Overdose from hydroxyzine is most commonly characterized by hypersedation, but may also manifest as convulsions, stupor, nausea, and vomiting. In cases of overdose, consider the induction of vomiting and the use of gastric lavage. Other treatment should involve general symptomatic and supportive care. Hypotension may be controlled by intravenous fluids and pressors, and caffeine and sodium benzoate injection may be used to counteract any observed CNS depressant effects. Hemodialysis is unlikely to provide any benefit in the treatment hydroxyzine overdose.


Patient with porphyria, suffering from glaucoma, bladder outflow obstruction, decreased GI motility, myasthenia gravis, or dementia; with known predisposing factor to cardiac arrhythmia, including electrolyte imbalance, increased potential for convulsions, and pre-existing heart disease. Do not admin via SC, IV, or intra-arterial inj. Renal and hepatic impairment.


Additive or may potentiate CNS depressant effects of opiates or other analgesics, barbiturates or other sedatives, and anaesth. MAOIs and TCAs potentiate antimuscarinic effects.

Food Interaction

  • Avoid alcohol. Co-administration with alcohol may potentiate the CNS adverse effects of hydroxyzine.
  • Avoid grapefruit products. Co-administration with grapefruit inhibits hydroxyzine metabolism and can result in elevated serum concentrations.

[Moderate] GENERALLY AVOID: Alcohol may potentiate some of the pharmacologic effects of CNS-active agents.

Use in combination may result in additive central nervous system depression and
MANAGEMENT: Patients receiving CNS-active agents should be warned of this interaction and advised to avoid or limit consumption of alcohol.

Ambulatory patients should be counseled to avoid hazardous activities requiring complete mental alertness and motor coordination until they know how these agents affect them, and to notify their physician if they experience excessive or prolonged CNS effects that interfere with their normal activities.

Volume of Distribution

The mean volume of distribution is 16.0 ± 3.0 L/kg. Higher concentrations are found in the skin than in the plasma.

Elimination Route

The absolute bioavailability of hydroxyzine has not been ascertained, as intravenous formulations are unavailable due to a risk of hemolysis. Hydroxyzine is rapidly absorbed from the gastrointestinal tract upon oral administration, reaching its maximum plasma concentration (Tmax) approximately 2 hours following administration.

Half Life

The half-life of hydroxyzine is reportedly 14-25 hours, and appears to be, on average, shorter in children (~7.1 hours) than in adults (~20 hours). Elimination half-life is prolonged in the elderly, averaging approximately 29 hours, and is likely to be similarly prolonged in patients with renal or hepatic impairment.


Clearance of hydroxyzine has been reported to be 31.1 ± 11.1 mL/min/kg in children and 9.8 ± 3.3 mL/min/kg in adults.

Elimination Route

Approximately 70% of hydroxyzine's active metabolite, cetirizine, is excreted unchanged in the urine. The precise extent of renal and fecal excretion in humans has not been determined.

Pregnancy & Breastfeeding use

Pregnancy Category C. Either studies in animals have revealed adverse effects on the foetus (teratogenic or embryocidal or other) and there are no controlled studies in women or studies in women and animals are not available. Drugs should be given only if the potential benefit justifies the potential risk to the foetus.

Nursing mothers: It is not known whether this drug is excreted in human milk. Since many drugs are so excreted, hydroxyzine should not be given to nursing mothers.


Hydroxyzine, when administered to the pregnant mouse, rat, and rabbit, induced fetal abnormalities in the rat and mouse at doses substantially above the human therapeutic range. Clinical data in human beings are inadequate to establish safety in early pregnancy. Until such data are available, hydroxyzine is contraindicated in early pregnancy. Hydroxyzine is contraindicated for patients who have shown a previous hypersensitivity to it.

Special Warning

Renal Impairment: Moderate to severe: Reduce dose by 50%.

Hepatic Impairment: Oral: Reduce total daily dose by 33%.

Geriatric use: A determination has not been made whether controlled clinical studies of hydroxyzine included sufficient numbers of subjects aged 65 and over to define a difference in response from younger subjects. Other reported clinical experience has not identified differences in responses between the elderly and younger patients. In general, dose selection for an elderly patient should be cautious, usually starting at the low end of the dosing range, reflecting the greater frequency of decreased hepatic, renal or cardiac function, and of concomitant disease or other drug therapy.

The extent of renal excretion of hydroxyzine has not been determined. Because elderly patients are more likely to have decreased renal function, care should be taken in dose selections. Sedating drugs may cause confusion and over sedation in the elderly; elderly patients generally should be started on low doses of hydroxyzine and observed closely.

Acute Overdose

Symptoms: Excessive sedation, hypotension (rare).

Management: Symptomatic and supportive treatment. Empty stomach immediately by inducing emesis or by gastric lavage. Admin IV fluids and norepinephrine or metaraminol if hypotension occurs.

Storage Condition

Store between 15-30° C. Protect from light.

Innovators Monograph

You find simplified version here Hydroxyzine

Hydroxyzine contains Hydroxyzine see full prescribing information from innovator Hydroxyzine Monograph, Hydroxyzine MSDS, Hydroxyzine FDA label


What is Hydroxyzine used for?

Hydroxyzine is used in the treatment of itchiness, and nausea, including that due to motion sickness. It is used either by mouth or injection into a muscle. It can also be used to help control anxiety and produce sleep before surgery.

How safe is Hydroxyzine?

It is a safe and effective medication when used as directed. Physician should reassess periodically the usefulness of the drug for the individual patient.

How does Hydroxyzine work?

Hydroxyzine works by blocking the action of histamine a substance in the body that causes allergic symptoms. It also works by decreasing activity in the brain.

What are the common side effects of Hydroxyzine?

Drowsiness, dizziness, blurred vision, constipation, or dry mouth may occur. If any of these effects persist or worsen, tell your doctor or pharmacist promptly. To relieve dry mouth, suck (sugarless) hard candy or ice chips, chew (sugarless) gum, drink water, or use a saliva substitute.

Is Hydroxyzine safe during pregnancy?

You should not use Hydroxyzine if you are pregnant, especially during the first or second trimester. Hydroxyzine could harm the unborn baby or cause birth defects. Use effective birth control to prevent pregnancy while you are using this medicine.

Is Hydroxyzine safe during breastfeeding?

Small occasional doses of Hydroxyzine would not be expected to cause any adverse effects in breastfed infants.

Can I drink alcohol with Hydroxyzine?

It is best to avoid alcohol use if you take Hydroxyzine.

Can I drive after taking Hydroxyzine?

Do not drive, operate machinery, or perform tasks requiring alertness if this medicine makes you drowsy. Hydroxyzine is available as capsules and an oral suspension.

When should be taken of Hydroxyzine?

Hydroxyzine may be taken with or without food. Take with food if you experience an upset stomach. Hydroxyzine may be taken every day at regular times or on an as needed basis.

How often can I take Hydroxyzine?

Hydroxyzine 50 to 100 milligrams (mg) 4 times a day.

How long does Hydroxyzine take to work?

Hydroxyzine starts working very quickly. Most people will start to feel it kick in within 30 minutes and will feel its maximum effect at around 2 hours.

How long does Hydroxyzine stay in my system?

Typically, it takes about five half-lives for a drug to completely leave your system. For Hydroxyzine, this means the drug will stay in your system for about 70 hours after your last dose.

Can I take Hydroxyzine for a long time?

Hydroxyzine is for short-term use only. You should not take this medicine for longer than 4 months.

What happens if I miss a dose?

Take the missed dose as soon as you remember. Skip the missed dose if it is almost time for your next scheduled dose. Do not take extra medicine to make up the missed dose.

What happens if I overdose?

Seek emergency medical attention. Overdose symptoms may include severe drowsiness, nausea, vomiting, uncontrolled muscle movements, or seizure (convulsions).

Who should not take Hydroxyzine?

Your doctor will probably tell you not to take Hydroxyzine. ell your doctor if anyone in your family has or has ever had a prolonged QT interval or if you have or have ever had a slow or irregular heartbeat, low blood levels of potassium or magnesium, heart failure, a heart attack, or heart disease.

What happens if I just stop taking Hydroxyzine?

This means your body starts to need the medication to function normally, and if you suddenly stop taking it, you may experience withdrawal symptoms.

Can Hydroxyzine affects my heart ?

Hydroxyzine can cause a serious heart problem, especially if you use certain medicines at the same time, including antibiotics, antidepressants, heart rhythm medicine, antipsychotic medicines, and medicines to treat cancer, malaria, HIV or AIDS.

Is Hydroxyzine safe for kidney patients?

Only your physician can safely prescribe you medication. I have safely used Hydroxyzine in patients with chronic kidney disease. You should consult with your physician.

Can Hydroxyzine affects my liver?

Hydroxyzine has not been linked to liver test abnormalities or to clinically apparent liver injury.

*** Taking medicines without doctor's advice can cause long-term problems.