According to the Centers for Disease Control and Prevention (CDC), nearly 33% of adults and more than 25% of children had at least one allergy in 2021. While functional and integrative medicine approaches excel at addressing the root causes of allergies and guiding individuals toward long-term symptom control, there are times when immediate relief is necessary.
Allergy symptoms like persistent sneezing, itching, or hives can significantly interfere with daily life, prompting the need for a quick-fix solution. With an array of antihistamines and allergy medications available, you might need help figuring out where to start. One option worth exploring is hydroxyzine – a versatile antihistamine often prescribed for allergies and related conditions.
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What Is Hydroxyzine?
Hydroxyzine is an H1 antihistamine, a medication designed to block the effects of histamine. Histamine is a natural chemical released by immune cells in response to allergens. It triggers symptoms like sneezing, itching, runny nose, and hives by binding to H1 receptors in tissues such as the skin, airways, and nasal passages.
Hydroxyzine is classified as a first-generation antihistamine, distinguishing it from newer, second-generation antihistamines. First-generation antihistamines are known for their ability to cross the blood-brain barrier (BBB), allowing them to affect the central nervous system. This property is responsible for one of hydroxyzine's most notable side effects: drowsiness. (2)
The U.S. Food and Drug Administration (FDA) has approved hydroxyzine for the following uses in children and adults:
- Relief of itching caused by allergic conditions
- Symptomatic relief of anxiety
- Provide sedation before surgery or other medical procedures
Hydroxyzine comes in hydrochloride and pamoate forms. Hydroxyzine hydrochloride and hydroxyzine pamoate are two versions of the same medication that differ in how they are made.
- Hydroxyzine hydrochloride is available in generic form as a tablet, syrup, oral solution, and intramuscular injection.
- Hydroxyzine pamoate is only made as a capsule. It is available as a generic and brand (Vistaril) medication.
Common Hydroxyzine Side Effects
The FDA reports dry mouth and excessive sleepiness as hydroxyzine's most common side effects. These usually do not require medical attention and often self-resolve within a few days to weeks.
Other mild side effects reported with hydroxyzine use include:
- Constipation
- Difficulty concentrating
- Headache
- Weakness
Serious Hydroxyzine Side Effects: When to Seek Medical Help
Serious side effects aren't common with hydroxyzine use but can occur. These may include:
- A lengthening of part of the heart rhythm called the QT interval, which increases the risk of abnormal heart rhythms, including a life-threatening arrhythmia called torsade de pointes.
- A severe skin condition called acute generalized exanthematous pustulosis, characterized by the sudden appearance of pin-head-sized pustules and skin discoloration.
- Confusion
- Seizures
- Allergic reactions
Patients who experience the following symptoms when taking hydroxyzine should seek immediate medical attention (3, 15):
- Decreased awareness or responsiveness
- Nausea and vomiting
- Involuntary muscle movements and convulsions
- Irregular heartbeat
- Chest pain or discomfort
- Fainting
- Skin rash or hives
- Difficulty breathing
- Swelling of the face, mouth, tongue, or throat
Long-Term Use: Potential Risks and Considerations
Research indicates that long-term use of hydroxyzine may be associated with cognitive decline. A population-based longitudinal study found that children under the age of five who frequently took hydroxyzine had significantly higher rates of mental and psychomotor disorders, including tics, anxiety, and conduct disturbances. The odds ratios for these conditions were notably higher in children with repeat prescriptions than those with a single prescription.
While the direct evidence linking hydroxyzine to long-term cognitive decline in adults is limited, the drug's anticholinergic properties raise concerns. Anticholinergic medications block the effects of the neurotransmitter acetylcholine. They have been associated with cognitive impairment and dementia in older adults.
While hydroxyzine is not typically associated with the same level of dependency as benzodiazepines or opioids, there have been reports of withdrawal symptoms, particularly in neonates born to mothers who were on long-term hydroxyzine therapy. This suggests that dependency can develop with prolonged use. Withdrawal symptoms from hydroxyzine may include:
- Tremors and seizures
- Rebound anxiety
- Insomnia
- Irritability
- Headache
- Dizziness
- Nausea and vomiting
Special Populations and Hydroxyzine Use
Pregnancy: The FDA classifies hydroxyzine as a pregnancy Category C drug, meaning animal studies have shown some potential risks to the fetus, but adequate human studies are lacking. Specifically, animal studies suggest that hydroxyzine may have teratogenic effects (i.e., the potential to cause congenital defects) when administered during pregnancy. Due to these findings, hydroxyzine is contraindicated during early pregnancy, particularly in the first trimester, when fetal development is most vulnerable. (23)
Breastfeeding: Hydroxyzine is generally not recommended for breastfeeding individuals because it can pass into breast milk and may cause sedation or other effects in the nursing infant. (23)
Geriatric Use: Hydroxyzine is included in the Beers Criteria, a guideline identifying medications that may be inappropriate for older adults due to their risk profile. Its sedative and anticholinergic effects can increase the likelihood of confusion, dizziness, dry mouth, constipation, urinary retention, and falls, which are particularly dangerous in this population. As a result, hydroxyzine is generally avoided in elderly patients unless absolutely necessary. It should be used at the lowest effective dose with close monitoring when prescribed. (23)
Drug Interactions and Contraindications
Hydroxyzine can interact with certain medications and supplements. Examples of drugs that can interact and should not be taken with hydroxyzine include (3, 17):
- Medications that prolong the QT interval, such as amiodarone, citalopram, haloperidol, levofloxacin, and methadone
- Central nervous system depressants, including opioids, sleep medications, benzodiazepines, and alcohol
- Anticonvulsant medications, such as phenytoin and phenobarbital
- Drugs metabolized by CYP2D6, including fluoxetine and codeine
Note that this is not a complete list of possible drug interactions. Always tell your doctor what other medications and supplements you are taking to avoid adverse reactions.
Do not use hydroxyzine in the following scenarios:
- Early pregnancy
- History of hypersensitivity (allergy) to hydroxyzine, cetirizine (Zyrtec), or levocetirizine (Xyzal)
- A heart rhythm condition called long QT syndrome
Managing Hydroxyzine Side Effects and Minimizing Risk
Managing these side effects involves a proactive approach by healthcare providers and patients to ensure safety and maximize therapeutic benefits.
Dosage Adjustments: Careful dosing is one of the most effective ways to minimize side effects. Doctors can prescribe hydroxyzine at the lowest dose and gradually increase it as needed for symptom control. Dosing recommendations are as follows:
Monitoring and Follow-Up: Regular follow-up appointments help evaluate the medication's efficacy and identify side effects early. Patients are encouraged to keep a record of any side effects they experience and share this information with their healthcare provider. Symptoms such as extreme drowsiness, confusion, or difficulty urinating should be reported immediately.
Alternative Medications: Healthcare providers may recommend alternative treatments if side effects become intolerable. Second-generation antihistamines, such as loratadine or cetirizine, can provide similar benefits for allergy management without the sedative effects of hydroxyzine. For anxiety, other non-sedating options may be more appropriate.
Instructions for Patients: Patients should take hydroxyzine exactly as prescribed, adhering to dosage instructions and avoiding alcohol consumption, which can amplify sedative effects. Activities requiring focus, such as driving or operating heavy machinery, should be avoided until the individual understands how hydroxyzine affects them.
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Key Takeaways
- Hydroxyzine is a first-generation antihistamine that can be effective in managing allergies and anxiety.
- Like any medication, hydroxyzine holds the potential to cause unwanted side effects. Most are mild and transient, but more severe side effects, like abnormal heart rhythm and oversedation, can occur.
- Strategies to prevent and manage side effects include starting with the lowest effective dose, regular monitoring by healthcare providers, and prompt patient reporting of any adverse effects.
- Alternative medications may offer a safer solution for individuals who experience intolerable side effects.
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