Hydroxyzine hydrochloride (tablet)
Hydroxyzine is an antihistamine belonging to the first‑generation (sedating) class. In tablet form it’s prescribed for a variety of conditions, largely because of its strong antihistaminic, anti‑emetic, anxiolytic, and sedative properties.
| Primary uses | Typical therapeutic benefit |
|--------------|-----------------------------|
| Allergic reactions – urticaria, pruritus, allergic dermatitis, allergic rhinitis, insect‑bites | Relief of itching, redness, hives, and swelling |
| Anxiety & pre‑operative sedation – mild to moderate anxiety | Calms patients before surgery or dental procedures and reduces peri‑operative anxiety |
| Nausea & vomiting – motion sickness, postoperative or chemotherapy‑induced nausea | Decreases nausea, prevents vomiting |
| Sleep aid – short‑term insomnia related to anxiety or allergic symptoms | Sedation that helps patients fall asleep |
| Adjunct in other conditions – e.g., chronic pain or spastic disorders (rarely) | Mild muscle relaxation and analgesic synergy when combined with opioids |
| Anti‑emetic for chemotherapy (in some regions) | Reduces chemo‑related nausea and vomiting when used with other agents |
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How it works
- H1 receptor antagonist – blocks histamine at peripheral and central sites, providing antihistamine and sedative effects.
- Centrally acting – reduces activity in the medullary vomiting center and the limbic system, producing anxiolysis and sedation.
- Inhibits acetylcholine release – contributes to anti‑emetic and sedative actions.
Typical dosing (adult)
| Indication | Starting dose | Max dose | Administration |
|------------|---------------|----------|----------------|
| Allergic rhinitis, urticaria | 25 mg 2–3 × day | 150 mg/day (divided) | With or without food |
| Anxiety / pre‑operative | 50–100 mg 30 min before surgery | 200 mg/day | Oral |
| Nausea/vomiting (e.g., motion) | 25–50 mg 30 min before activity | 200 mg/day | Oral |
| Sleep aid (short‑term) | 25–50 mg 30 min before bedtime | 50–100 mg/day | Oral |
Children, elderly, and patients with hepatic or renal impairment may need lower doses.
Important warnings & precautions
| Category | Key points |
|----------|------------|
| Sedation & CNS | Strongly sedative. Avoid driving, operating machinery, or alcohol. Can cause impaired concentration. |
| Anticholinergic effects | Dry mouth, blurred vision, urinary retention, constipation, constipation. |
| Cardiovascular | Can prolong QT interval, especially in overdose or when combined with other QT‑prolonging drugs (e.g., macrolide antibiotics, antipsychotics). |
| Drug interactions | Additive sedation with benzodiazepines, opioids, alcohol, alcohol‑like CNS depressants. Interaction with CYP1A2 or CYP3A4 inhibitors/inducers can alter levels. |
| Pregnancy & lactation | Category B (rats) but limited human data; use only if benefits outweigh risks. |
| Use with caution | In patients with asthma, COPD, glaucoma, or myasthenia gravis, as anticholinergic effects can worsen symptoms. |
| Overdose | Symptoms: severe drowsiness, respiratory depression, hypotension, arrhythmias. Treatment: supportive care, activated charcoal, monitor cardiac status. |
Common side effects
- Drowsiness, fatigue, dizziness
- Dry mouth, blurred vision
- Headache, nausea
- Rare: paradoxical excitement, agitation (especially in children)
- Rare: hypersensitivity reactions (rash, anaphylaxis)
Storage
Keep in a cool, dry place, out of reach of children. Store below 25 °C (77 °F).
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Bottom line
Hydroxyzine tablets are a versatile sedating antihistamine used mainly for allergic reactions, mild anxiety, pre‑operative sedation, nausea, and occasional insomnia. Because of its strong sedative and anticholinergic effects, it should be used cautiously, especially in patients with CNS depression risk factors or when combined with other CNS‑depressing medications. Always follow your prescriber’s dosing instructions and report any concerning side effects.