Hydroxyzine is a prescription antihistamine medication used to manage anxiety, insomnia, and itching caused by allergic reactions. It works by blocking histamine, a natural substance in the body that can cause itching and other symptoms. The medication is available in different forms, such as tablets, capsules, and syrups, and can also be administered through intramuscular injection.
How Long Hydroxyzine’s Effects Last
Hydroxyzine typically begins to work within 15 to 30 minutes after being taken orally, with effects peaking around two hours. Sedative effects, often sought for anxiety or sleep, generally last between 4 to 6 hours. While noticeable effects subside quickly, the drug and its active metabolite cetirizine remain in the body for a longer period.
The elimination half-life of hydroxyzine in adults typically ranges from 14 to 25 hours, meaning it takes this long for half of the drug to be cleared. It generally takes about five half-lives for a medication to be almost completely eliminated. Therefore, hydroxyzine can remain detectable for approximately 70 to 125 hours, or roughly 3 to 5 days, even after its noticeable effects have worn off.
Factors Affecting Duration
The duration of hydroxyzine’s effects can vary significantly among individuals due to several physiological factors. Individual metabolism plays a substantial role, as people process drugs at different rates. For instance, the elimination half-life of hydroxyzine is shorter in children (around 7.1 hours) compared to adults (about 20 hours).
Age also influences how long hydroxyzine remains active; older adults, particularly those over 65, may experience a prolonged half-life, extending to approximately 29 hours. This is due to age-related changes in liver and kidney function, which are the primary organs responsible for metabolizing and eliminating the drug. Impaired liver or kidney function can lead to drug accumulation, potentially prolonging its effects and increasing the risk of side effects.
Dosage directly impacts duration; higher doses generally take longer to process and eliminate. Concurrent use of other medications can affect hydroxyzine’s metabolism and duration. Some drugs can interact with hydroxyzine, either slowing its elimination or enhancing its sedative effects.
Managing Persistent or Unwanted Effects
If the effects of hydroxyzine last longer than expected or if unwanted side effects occur, it is important to take appropriate action. Common side effects include drowsiness, dizziness, and dry mouth. Fatigue, blurred vision, confusion, irritability, headache, and urinary retention are also possible. These mild effects often resolve within a few days or weeks as the body adjusts.
However, if side effects are severe, persistent, or concerning, such as changes in heart rhythm, extreme confusion, or convulsions, immediate medical attention is necessary. Patients should contact a healthcare professional if they experience a fast, pounding, or uneven heartbeat, or if they feel dizzy or faint. Avoid activities requiring mental alertness, such as driving or operating heavy machinery, until you understand how hydroxyzine affects you. Always adhere to the prescribed dosage, as higher doses can increase the risk of serious side effects.