Hydroxyzine Side Effects


Do you ever wonder what the side effects are of the medicines your doctor has prescribed you?

Are you intimidated by the huge list of complex scientific terms that the patient information leaflet lists as side effects?1

It is not surprising that as modern medicine advances, so too has the idea of ‘patient autonomy’ a patient’s right to have full control over anything done to his or her body. Therefore, in line with this idea, it is valid that you may want to clearly understand your medicine's side effects. In this case, the side effects of hydroxyzine will be explained. 

Hydroxyzine is an antihistamine that is prescribed in the UK for pruritus – a skin condition that causes itching, anxiety relief, and sedation before an operation. 

What is hydroxyzine?

In its essence, Hydroxyzine is an antihistamine. What does this mean? The body has areas where histamine a substance that exists naturally inside us can bind and produce effects. These areas are also called receptors. 2 These receptors exist throughout the body and in turn, also in the brain and the central nervous system (CNS). Antihistamines can travel through the blood into the brain and stop histamine from attaching to these receptors.2 The main areas where histamine has effects are the muscles of the intestine, blood vessels and throat,  the heart, the central nervous system, the immune system and the endocrine system(a group of glands and organs involved in many body functions, such as sleeping and waking cycles)

What is hydroxyzine used for?

If you have ever been prescribed Hydroxyzine, then you will be aware that it is commonly used for the following reasons :itching of the skin, anxiety and pre-medication before an operation.2

In the UK hydroxyzine is prescribed as Ucerax or Atarax.

Skin conditions 

Pruritus means ‘itchy skin’. The itch can become so intense that it encourages you to scratch, and over long periods can be difficult on your quality of life. It occurs in around 13.8% of adults and increases to 16.8% in cancer patients, and it can present in specific areas of your body or all over.3 It can be a one-off experience or, if it lasts longer (more than 6 weeks) it is known as chronic pruritus. 

What causes this itch? There are several causes of pruritus and swelling and redness of the skin may also be present: 

  • Skin reaction – to heat, or to something you are allergic to. This is usually referred to as hives or prickly heat 
  • Longterm Itch (chronic pruritus) – dandruff, eczema or psoriasis
  • Fungal skin infections – thrush, ringworm and athlete’s foot. These conditions will always present with irritation to the skin such as redness or swelling
  • Pregnancy and menopause – hormonal changes can cause your skin to itch

Sometimes the presence of chronic pruritus is a sign that there is something wrong inside your body:4 

  • Inflammation
  • Infection
  • Autoimmune disease
  • Liver disease
  • Kidney disease
  • Nerve conditions
  • Psychological conditions

If your skin is itching for long periods and is affecting your daily life, you should speak with your GP. If you notice any new lumps or red swellings that do not resolve on their own, again you must speak with your GP. 

So, how does hydroxyzine help in pruritus? The itch in the skin is caused by histamine being released from cells. After it is released, it stimulates nerves, which itch sensation. Hydroxyzine then blocks histamine from having these effects- hence the term antihistamine.5

Anxiety relief

Hydroxyzine is commonly used in anxiety disorder management.6 Anxiety is the most common group of mental disorders and The World Health Organisation has classified these disorders as the 9th most health-related cause of disability.7

It presents as excessive fear and anxiety or avoidance of things which are perceived as threats, including people, places and situations.

Evidence shows dysfunction in the brain’s ability to respond to danger in people with an anxiety disorder.8 So, if you have been diagnosed with an anxiety disorder, you will perceive certain people/situations/places as threats that other people do not. Although we all experience fear, if you suffer from an anxiety disorder, your fear usually disrupts your day-to-day life. Not only do anxiety sufferers experience fear in their minds, but they also feel it in their bodies. This can present in the form of heart palpitations increased heart rate, or shortness of breath. It is clear, therefore, why some people may need medicines to help with their anxiety.

Hydroxyzine’s ability to help relieve anxiety symptoms is related to blocking histamine from working in certain areas of the brain.8 The hypothalamus, the part of the brain which controls our ‘Sleep-wake cycle’, is the main area where antihistamines hydroxyzine acts. During the day, histamine is working in the hypothalamus to keep you awake. 6,8 So, what happens if histamine can't do its job during the day? The answer is sedation or drowsiness.8 Hydroxyzine works by stopping histamine, keeping you awake: as it is given in low doses, it doesn’t cause you to fall asleep. If you have been functioning in an anxious state, some sedation is beneficial to quite literally ‘calm your nerves’.8 

Sedation before anaesthesia 

If you have ever had an operation, you may have been given some medicine before you go into the theatre/operating room and receive the anaesthesia. This is called pre-medication and is given to patients to help reduce their anxiety and awareness of the surgery.9 Hydroxyzine’s sedating effects are beneficial as a pre-medication. 

Possible side effects

More and more evidence shows that involving patients in their healthcare leads to better health outcomes.10 Therefore, nowadays, when you receive your medicine from the pharmacy, it comes with a patient information leaflet (PIL) where all the side effects are listed. In Europe, these leaflets have a list of side effects with the probability that they will happen e.g. very common means that they might affect more than 1 in 10 people.10 It is important to note that, because the PIL says a side effect is very common, or common, it does not mean that you will experience it. 

Hydroxyzine has different kinds of side effects, based on it acting on different areas throughout the body. The following side effects have been reported in hydroxyzine tablets in doses up to 50 mg daily. They are usually mild and transitory.11

It is important to note that the side effects of medicines depend on several factors:

  • The dose you are taking
  • Your age
  • Your other health conditions
  • The other medicines you are taking 

Common side effects

The most common side effects of hydroxyzine, those which may occur in up to 1 in 10 people, are:2,11

  • Headache
  • Dry mouth (xerostomia)
  • Sleepiness (fatigue) – this usually doesn’t last long and should disappear within a few days of starting the medicine

Those side effects that happen less commonly –less than 1 in 100 people but more than 1 in 1000 people are:2,10

  • Dizziness
  • Constipation
  • Nausea 
  • Asthenia- lack of energy 

Serious side effects

Like many medicines, hydroxyzine can have some serious side effects. If you are experiencing any of these after starting this therapy, then call your doctor immediately. 

  • Abnormal heart rhythms – known as long QT syndrome or torsades de pointes
  • Skin reactions – see skin reaction section below
  • Allergic reaction – see allergic reaction section below

Skin reactions 

It is possible to have serious skin reactions while taking hydroxyzine such as:

Allergic reactions 

Although not listed as a common side effect, people can experience allergic reactions to hydroxyzine. 

The following symptoms are not classed as a serious reaction:

  • Skin rash
  • Itchiness
  • Flushing- when the skin becomes temporarily warm and red

More serious allergic reactions, although rare, can occur; the main symptom is swelling. It can present under the skin and affects your lips, hands and feet. The swelling can also extend to your mouth and, in turn, can cause breathing difficulties. These symptoms are very serious and you must call an ambulance, or attend an accident and emergency if you have them.

Limiting side effects

As mentioned above, hydroxyzine has some side effects that are more serious than others. As the dose increases, so too can the chances that these effects may happen.2

In the following cases, the lowest dose for the shortest time is recommended to reduce the chance of side effects:

  • Cardiovascular effects – there is a small chance that hydroxyzine may alter the electrical activity of the heart, especially if you already have heart rhythm problems. If you are at high risk, hydroxyzine won’t be used
  • Convulsions – if you have a history of convulsions, your doctor will prescribe you a reduced dose
  • Anticholinergic effects – hydroxyzine can affect some existing conditions you may already have such as glaucoma, myasthenia gravis, dementia, decreased gut motility and bladder obstruction. In these instances, your GP may recommend a lower dose or no use of the medicine at all
  • Kidney and Liver Impairment – due to the way hydroxyzine is removed from your body, if you have any kidney or liver issues you may not be able to take hydroxyzine, or a lower dose will be prescribed
  • Alcohol –  although this is not a side effect of hydroxyzine, it is important to mention that when taken together, alcohol can worsen the side effects of hydroxyzine. The main symptoms are dizziness, fatigue, nausea and sleepiness. It is not recommended to drink alcohol with hydroxyzine

When to see a doctor

You should speak with your doctor immediately if you are experiencing any of the side effects listed in the serious side effects section, especially if they do not appear to be resolving.

With regards to seeking urgent medical attention, this would be the case in the following instances: 2

  • Painful areas of the skin accompanied by blisters and fever
  • Swelling under the skin can affect your hands, and lips and that extends to your throat making it hard to breathe

It is important to note that your GP will assess your health history for any underlying conditions which could lead to serious side effects of this medicine. These are examples of possible effects, but that are statistically rare- they don’t happen often.12

Alternatives to hydroxyzine

Hydroxyzine is contraindicated in several different conditions; therefore, some alternatives can be used in its place.

For itching of the skin – there are some non-drowsy antihistamines that your GP can prescribe instead of hydroxyzine. Loratadine, desloratadine and fexofenadine are all examples of non-sedating antihistamines that can help relieve an itch, without producing any side effects in the brain.13

For anxiety – Nowadays, selective serotonin reuptake inhibitors (SSRI’s) are the first-line therapies in anxiety management.14 Their side effect profile does not contain as many ‘limiting’ side effects as hydroxyzine. Evidence has shown they are well tolerated by patients in the long term.12 Some examples of these drugs are duloxetine, citalopram and escitalopram. 


Hydroxyzine is a medicine that belongs to the group of drugs called antihistamines. It works in your body by stopping histamine, a naturally occurring chemical, from doing its job. It is mainly used to treat itching in skin conditions, relieve anxiety symptoms and in premedication before operation. Due to its ability to work in many different parts of your body – including your brain – hydroxyzine can cause several side effects. These tend to resolve after some time of taking hydroxyzine.

Hydroxyzine also has many limiting side effects, which means that the lowest dose for the shortest time possible is recommended. If you have a number of pre-existing conditions such as abnormal heart rhythms, a history of convulsions, glaucoma, gut issues, bladder problems or kidney or liver problems, your doctor will alter the dose or may suggest an alternative. It is important not to drink alcohol while taking this medicine as it makes the side effects worse.

You need to see a doctor after starting hydroxyzine if you experience any of the side effects listed in the serious side effects section, especially if they are not resolving. You must seek urgent medical attention if you have any of the following after starting hydroxyzine: painful areas of skin with fever and blisters, or swelling which starts in the hands, feet or lips and that extends to the throat. 


  1. Ziegler, Dewey K., et al. ‘How Much Information About Adverse Effects of Medication Do Patients Want From Physicians?’ Archives of Internal Medicine, vol. 161, no. 5, Mar. 2001, p. 706. DOI.org (Crossref), https://doi.org/10.1001/archinte.161.5.706.
  2. Powell, Kim. Histamine Receptors. Edited by S. J. Enna and David B. Bylund, Elsevier, 2007, pp. 1–2. ScienceDirect, https://doi.org/10.1016/B978-008055232-3.60127-8.
  3. Thomas, Jayakar, et al. ‘Real-World, Non-Interventional, Observational Study of Hydroxyzine Hydrochloride in Chronic Pruritus: A Prospective, Non-Comparative Study’. Dermatology and Therapy, vol. 9, no. 2, June 2019, pp. 299–308. DOI.org (Crossref), https://doi.org/10.1007/s13555-019-0293-2.
  4. Ständer, Sonja, et al. ‘Editorial: Pruritus Medicine’. Frontiers in Medicine, vol. 8, Sept. 2021, p. 763667. PubMed Central, https://doi.org/10.3389/fmed.2021.763667.
  5. Rossbach, K., et al. ‘Histamine H1, H3 and H4 Receptors Are Involved in Pruritus’. Neuroscience, vol. 190, Sept. 2011, pp. 89–102. ScienceDirect, https://doi.org/10.1016/j.neuroscience.2011.06.002.
  6. Thakkar, Mahesh M. ‘Histamine in the Regulation of Wakefulness’. Sleep Medicine Reviews, vol. 15, no. 1, Feb. 2011, pp. 65–74. ScienceDirect, https://doi.org/10.1016/j.smrv.2010.06.004.
  7. Penninx, Brenda WJH, et al. ‘Anxiety Disorders’. The Lancet, vol. 397, no. 10277, Mar. 2021, pp. 914–27. ScienceDirect, https://doi.org/10.1016/S0140-6736(21)00359-7.
  8. Saxen, Mark A. Chapter 17 - Pharmacologic Management of Patient Behavior. Edited by Jeffrey A. Dean, Mosby, 2016, pp. 303–27. ScienceDirect, https://doi.org/10.1016/B978-0-323-28745-6.00017-X.
  9. Franssen, Colette, et al. ‘Comparison between Alprazolam and Hydroxyzine for Oral Premedication’. Canadian Journal of Anaesthesia, vol. 40, no. 1, Jan. 1993. orbi.uliege.be, https://doi.org/10.1007/BF03009311.
  10. Knapp, Peter, et al. ‘Communicating the Risk of Side Effects to Patients: An Evaluation of UK Regulatory Recommendations’. Drug Safety, vol. 32, no. 10, Oct. 2009, pp. 837–49. DOI.org (Crossref), https://doi.org/10.2165/11316570-000000000-00000.
  11. DailyMed - HYDROXYZINE HYDROCHLORIDE- Hydroxyzine Tablet, Film Coated. https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=89901966-724b-4773-98b8-ea663ceabd53. Accessed 11 Aug. 2022.
  12. Garakani, Amir, et al. ‘Pharmacotherapy of Anxiety Disorders: Current and Emerging Treatment Options’. Frontiers in Psychiatry, vol. 11, 2020. Frontiers, https://www.frontiersin.org/articles/10.3389/fpsyt.2020.595584.
  13. Yanai, Kazuhiko, et al. ‘The Clinical Pharmacology of Non-Sedating Antihistamines’. Pharmacology & Therapeutics, vol. 178, Oct. 2017, pp. 148–56. ScienceDirect, https://doi.org/10.1016/j.pharmthera.2017.04.004.
  14. Recommendations | Generalised Anxiety Disorder and Panic Disorder in Adults: Management | Guidance | NICE. https://www.nice.org.uk/guidance/cg113/chapter/Recommendations#stepped-care-for-people-with-gad. Accessed 17 Aug. 2022.
This content is purely informational and isn’t medical guidance. It shouldn’t replace professional medical counsel. Always consult your physician regarding treatment risks and benefits. See our editorial standards for more details.

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Danielle Ferrie

Masters of Pharmacy - MPharm, University of Strathclyde, Scotland

Danielle is a Locum Pharmacist with strong business acumen having exposure to clinical and management roles between the hospital and community sectors.
She has several years of experience as a GPhC registered Pharmacist as well as an EFL Teacher working with University lecturers on editing articles.

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