From the Guidelines
Hydroxyzine is associated with significant side effects, including sedation, drowsiness, and anticholinergic effects, which can impair driving ability and cognitive function, particularly in elderly patients 1.
Common Side Effects
- Drowsiness and sedation
- Dry mouth
- Headache
- Constipation
- Blurred vision
- Difficulty urinating
- Confusion, particularly in elderly patients
Less Common Side Effects
- Dizziness
- Weakness
- Gastrointestinal disturbances like nausea or stomach upset
Rare Side Effects
- Heart rhythm changes, particularly QT interval prolongation, which can be problematic for people with heart conditions
- Allergic reactions, presenting as rash, itching, or more severe symptoms
Special Considerations
- Elderly patients are more sensitive to the psychomotor impairment and anticholinergic effects of hydroxyzine, and its use should be approached with caution in this population 1.
- The sedative effects of hydroxyzine can impair driving ability and cognitive function, so patients should avoid operating machinery or driving until they know how the medication affects them 1.
- Hydroxyzine can also cause cognitive decline, particularly in the elderly population, due to its anticholinergic effects 1.
Mechanism of Action
Hydroxyzine works by blocking histamine receptors in the brain and has additional anticholinergic properties that affect various body systems, leading to its side effects 1.
Dosage and Individual Sensitivity
The severity of side effects typically depends on dosage and individual sensitivity, with most being mild and diminishing as the body adjusts to the medication 1.
From the FDA Drug Label
Skin and Appendages: Oral hydroxyzine hydrochloride is associated with Acute Generalized Exanthematous Pustulosis (AGEP) and fixed drug eruptions in post marketing reports. 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 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 In post-marketing experience, the following additional undesirable effects have been reported: Cardiac System: QT prolongation, Torsade de Pointes. Body as a Whole: Allergic reaction. Nervous System: Headache. Psychiatric: Hallucination. Skin and Appendages: Pruritus, rash, urticaria.
The side effects of hydroxyzine include:
- Anticholinergic effects: dry mouth
- Central Nervous System effects: drowsiness, tremor, convulsions
- Cardiac System effects: QT prolongation, Torsade de Pointes
- Allergic reactions: allergic reaction, pruritus, rash, urticaria
- Nervous System effects: headache
- Psychiatric effects: hallucination As reported in the drug label 2.
From the Research
Side Effects of Hydroxyzine
- The side effects of hydroxyzine include sleepiness/drowsiness, with a higher rate compared to active comparators 3.
- Hydroxyzine has been associated with a risk of QT prolongation and torsade de pointes (TdP), particularly in patients with underlying medical conditions or concomitant medications that constitute additional risk factors 4.
- The risk of QT prolongation and TdP has led to regulatory advisories and a decrease in hydroxyzine initiation in some countries, such as the UK 5.
- Other potential side effects of hydroxyzine are not well-documented in the provided studies, but it is known to have anxiolytic efficacy and a beneficial effect on sleep 3, 6.
- It is essential to consider individual risk factors for arrhythmias and other patient-specific factors when prescribing hydroxyzine or alternative medications 7.
Comparison with Other Medications
- Hydroxyzine has been compared to other anxiolytic agents, such as benzodiazepines and buspirone, and found to be equivalent in terms of efficacy, acceptability, and tolerability 3.
- In terms of QT prolongation risk, hydroxyzine has been evaluated in the context of other medications, including selective serotonin reuptake inhibitors (SSRIs) 7.
- The choice of alternative medications should be based on individual risk factors for arrhythmias and other patient-specific factors 7.