Can hydroxyzine (antihistamine) cause nightmares?

Hydroxyzine Can Cause Nightmares

Yes, hydroxyzine can cause nightmares as a side effect, particularly when taken at bedtime. While hydroxyzine is commonly prescribed as a sedating antihistamine for conditions like pruritus, anxiety, and sleep disturbances, its effects on sleep architecture and dream states can lead to disturbing dreams in some patients.

Mechanism and Evidence

• Hydroxyzine is a first-generation antihistamine with significant central nervous system (CNS) effects that can alter sleep architecture and potentially trigger nightmares, particularly when used at bedtime 1
• Nightmares can be induced by drugs that affect neurotransmitters including serotonin, norepinephrine, and dopamine, as well as those affecting GABA and acetylcholine - all systems that hydroxyzine interacts with 2
• While not specifically listed as a common side effect in major guidelines, the sedative properties of hydroxyzine that affect sleep stages can contribute to disturbed dreaming 1

Risk Factors for Hydroxyzine-Induced Nightmares

• Bedtime dosing (hydroxyzine is often recommended at bedtime for pruritus and sleep disturbances) 2
• Higher doses (10-25 mg QID or at bedtime is standard dosing, with higher doses potentially increasing risk) 2
• Individual sensitivity to CNS effects of antihistamines 1
• Concurrent use with other medications that affect sleep architecture 1

Management of Hydroxyzine-Associated Nightmares

• Consider adjusting the timing of hydroxyzine administration (taking it earlier in the evening rather than immediately before bedtime) 1
• Dose reduction may help minimize nightmares while maintaining therapeutic benefit 1
• For patients requiring antihistamine therapy who experience nightmares with hydroxyzine, consider switching to a second-generation antihistamine with less CNS penetration for daytime use 1
• If hydroxyzine is specifically needed for its sedative properties, consider alternative sedative medications with different mechanisms of action 2

Other Important Considerations

• Hydroxyzine has significant sedative effects that can impair driving ability, work performance, and cognitive function even into the following day 1, 3
• Performance impairment can occur without subjective awareness of drowsiness 1
• Hydroxyzine has become increasingly identified in impaired driving investigations, raising concerns about its cognitive effects 3
• Unlike diphenhydramine, hydroxyzine is less likely to cause antimuscarinic effects but more likely to cause mild CNS depression 4

Special Populations

• Elderly patients should start with lower doses and be monitored closely, as they are more sensitive to psychomotor impairment and at increased risk for falls 1
• Hydroxyzine is contraindicated during early pregnancy 1
• Dose should be halved in moderate renal impairment and avoided in severe renal impairment 1

In clinical practice, if a patient reports nightmares while taking hydroxyzine, particularly when used at bedtime, consider this a potential medication side effect and adjust the regimen accordingly to improve quality of life and sleep.