What is Doxylamine?
Doxylamine is a first-generation antihistamine primarily used for:
✔ Short-term insomnia treatment (sleep aid)
✔ Allergy relief (hay fever, itching, hives)
✔ Nausea/vomiting (often combined with pyridoxine for morning sickness)
Brand Names:
- Unisom SleepTabs (USA)
- Restavit (Australia)
- Diclegis (doxylamine + pyridoxine for pregnancy nausea)
How Doxylamine Works
- Blocks histamine H1 receptors in the brain → sedation
- Also has anticholinergic effects (dries secretions, relaxes muscles)
Doxylamine Uses
1. Insomnia (Most Common Use)
- Dose: 25 mg, 30 mins before bedtime
- Duration: Short-term only (up to 2 weeks)
2. Pregnancy Nausea (Morning Sickness)
- Diclegis Formula: Doxylamine 10 mg + Pyridoxine (B6) 10 mg
- Dose: Typically 2 tablets at bedtime, may increase to 4 tablets/day
3. Allergies & Cold Symptoms
- Often combined with decongestants (e.g., NyQuil)
Doxylamine Side Effects
Common Side Effects
☑️ Drowsiness (can persist next morning → “hangover effect”)
☑️ Dry mouth, blurred vision
☑️ Constipation, urinary retention
☑️ Dizziness, clumsiness
Serious Side Effects (Rare)
⚠️ Confusion/hallucinations (especially in elderly)
⚠️ Irregular heartbeat (risk if overdosed)
⚠️ Severe allergic reactions (rash, swelling, trouble breathing)
Important Warnings
1. Drug Interactions
🚫 Alcohol → Dangerous sedation
🚫 Opioids, benzodiazepines → Respiratory depression risk
🚫 MAOIs → Hypertensive crisis
2. Who Should Avoid It?
- Elderly patients (high fall/confusion risk)
- Glaucoma, enlarged prostate, asthma patients
- Breastfeeding women (passes into milk)
3. Overdose Danger
- >50 mg can cause seizures, coma, death
- Symptoms: Extreme drowsiness, dilated pupils, erratic heartbeat
Safe Usage Tips
✔ Take only at bedtime (avoid driving next morning)
✔ Don’t use >7-10 days for insomnia (tolerance builds)
✔ Pregnant? Use only under OB/GYN supervision
Alternatives to Doxylamine
- Melatonin (for sleep, fewer side effects)
- Diphenhydramine (similar but shorter-acting)
- Ondansetron (for nausea, non-sedating)
