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How Long Does Hydroxyzine Stay in Your System?

If you are taking hydroxyzine, an antihistamine, you may wonder how long does hydroxyzine stay in your system. This is a common concern with hydroxyzine, as drowsiness is a known side effect, and caution is advised until it is out of your system.

In the Healing Us podcast, Dr. Ed Ratush explores the field of psychiatry, highlighting the importance of humility in treatment and the need for honest relationships with patients. He discusses the challenges in behavioral health, the use of mindfulness techniques, and the role of technology in recovery. Dr. Ratush also shares his thoughts on the future of AI in psychiatry and the continuous evolution of treatment practices, including how long medicines generally stay in the body.

This raises the question: how long does hydroxyzine stay in your system, and what might cause it to linger longer? Continue reading to know more.

What is Hydroxyzine?

Hydroxyzine is an antihistamine that blocks the action of histamine in the body, relieving itching due to allergic reactions. It’s also used to treat anxiety and tension in both children and adults. Additionally, hydroxyzine can be used as a sedative before and after surgery due to its ability to reduce activity in the central nervous system.

Hydroxyzine is commonly used for various conditions, such as anxiety, allergy itching, nausea, and vomiting. Many people who take hydroxyzine are curious about the duration of each dose’s effects. If you’re taking hydroxyzine, you might be curious to figure out how long it takes to notice its effects and how long does hydroxyzine stay in your system.

How long does Hydroxyzine Stay in Your System?

According to ScienceDirect, drugs stay in your body for about five half-lives on average. The half-life of hydroxyzine is about 20 hours, which means it stays in your system for around 100 hours, even though its effects usually wear off sooner.

Hydroxyzine half-life may vary based on age and kidney or liver health. Its effects peak at 2 hours, so it’s often prescribed 3-4 times daily. Always follow your doctor’s instructions. When you stop taking it, the elimination half-life determines how long it takes for half of the medication to leave your system.

Compared to other antihistamines like diphenhydramine (Benadryl), which has a half-life of 3-9 hours, hydroxyzine lasts much longer. It also outlasts loratadine, another antihistamine with a half-life of 8 hours. In treating anxiety, hydroxyzine’s duration is comparable to alprazolam, which has a half-life of 11 hours and a total body presence of about 55 hours.

How quickly does Hydroxyzine start working?

Hydroxyzine starts working usually within 15-30 minutes and reaches peak concentration in about two hours. Its sedative effects can last 4-6 hours, making it practical for acute symptoms. For most healthy individuals, hydroxyzine is eliminated from the body within 5 days after the last dose.

However, if you experience prolonged drowsiness or effects beyond this period, consult your healthcare provider, as it may indicate slower metabolism or interactions with other medications.

Factors affecting how long does Hydroxyzine stay in your system

Several factors can affect how long hydroxyzine stays in your system:

● Age

Hydroxyzine stays in a child’s system for less time than in an adult due to differences in metabolism.

● Liver and Kidney Function

If these organs are not working well, they may not clear hydroxyzine efficiently, leading to more extended presence in the body.

● Dosage

The amount and frequency of hydroxyzine you intake influences how long it remains in your system. Higher doses or more frequent use prolong its presence.

● Metabolic Rate

A faster metabolism breaks down hydroxyzine more quickly, shortening its duration.

● Body Mass

Generally, the drug stays longer in those who weigh more.

● Overall Health

Poor health can slow down the body’s ability to remove hydroxyzine, especially if liver or kidney function is compromised.

These factors vary among individuals and impact how long does hydroxyzine stay in your system. Always follow your doctor’s instructions for safe and effective use.

Hydroxyzine Side Effects

Hydroxyzine is an older type of antihistamine known as a first-generation antihistamine. These medications can penetrate the blood-brain barrier, which often causes side effects such as drowsiness and impaired coordination, even when taken at regular doses.

Common Side Effects of Hydroxyzine

  • Drowsiness
  • Daytime sleepiness
  • Headache
  • Dizziness
  • Dry mouth
  • Constipation
  • Confusion

Serious Side Effects of Hydroxyzine

  • Rash
  • Skin redness
  • Pus-filled or blister-like sores
  • Seizures
  • Unintentional tremoring, trembling, or shaking
  • Fever

Old people and individuals with liver or kidney disorders, as well as certain heart conditions, are at higher risk for side effects. If you experience severe side effects or suspect an overdose, seek immediate medical attention.

Hydroxyzine Dosage

Hydroxyzine is available in various forms, including oral tablets, capsules, solutions, and injections, each with different dosages depending on the condition being treated:

● Anxiety

Adults typically take 50 to 100 milligrams orally every six hours as needed or receive injections of 50 to 100 milligrams every four to six hours. Children’s dosages vary by age and weight.

● Itching/Hives

Adults usually take 25 milligrams orally every six to eight hours as needed. Children’s dosages depend on age and weight.

● Sedative Before Anesthesia

Adults may receive 25 to 100 milligrams via injection as a single dose or orally if needed. Children’s dosages depend on their weight.

Hydroxyzine is also prescribed off-label for conditions such as insomnia and nausea/vomiting:

● Insomnia

Adults may take 50 to 100 milligrams orally 30 to 60 minutes before bedtime. Pediatric use for insomnia is not recommended.

● Nausea and Vomiting

Injectable hydroxyzine is FDA-approved for adults, with 25 to 100 milligrams every four to six hours as needed. Oral use for nausea/vomiting varies from 25 to 100 milligrams every six to eight hours, depending on the patient’s needs.

Hydroxyzine may also be used off-label for seasonal allergies, although its side effects, such as dry mouth and drowsiness, can limit its use.

FAQs: How long does Hydroxyzine stay in your system?

Que: Does hydroxyzine stop working? 

Ans: Yes, taking hydroxyzine daily may become less effective over time as your body builds a tolerance.

Que: Is hydroxyzine safe? 

Ans: Hydroxyzine can cause a heart rhythm problem called QT prolongation, which can lead to serious or even fatal heart issues. Seek medical attention if you experience severe dizziness or fainting.

Que: How strong is hydroxyzine? 

Ans: Hydroxyzine is available in other strengths, strengths, and forms. It is available in 10 mg, 25 mg, and 50 mg strengths.

Que: What is hydroxyzine mainly used for? 

Ans: Hydroxyzine controls anxiety and tension, helps with sleep before surgery, and relieves allergy symptoms like itching and hives.

Que: How quickly does hydroxyzine leave your system? 

Ans: Hydroxyzine starts working within 15 to 60 minutes and reaches its peak effect in about two hours. It can stay in your body for up to 125 hours after the last dose.


In conclusion, hydroxyzine’s quick onset and effectiveness make it a valuable option for managing both allergies and anxiety. Hydroxyzine is a medication used to treat insomnia, anxiety, and itching. If you wonder how long does hydroxyzine stay in your system, it depends on various factors such as age, medical history, and body type.

A dose of hydroxyzine may start working as quickly as 15 to 60 minutes. Its half-life is about 20 hours, meaning it stays in your system for around 100 hours. Despite this, it reaches peak effectiveness in 2 hours and lasts 3 to 4 hours. Hydroxyzine works quickly, often within 15-30 minutes for allergies and 30-45 minutes for anxiety, making it suitable for acute issues.

It’s always recommended to consult your medical specialist or healthcare provider to determine what’s right for you.

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