Circadin Side Effects: Onset, Peak & Duration
Clinical timeline of Circadin (2mg prolonged-release melatonin) side effects in adults over 55. UK-licensed treatment.
Key Takeaways
- First signs: 1-4 hours after taking Circadin
- Peak intensity: 3-6 hours post-dose
- Typical duration: 6-24 hours (up to 48h in sensitive individuals)
- Most common: Headache (12%), dizziness (6%), nausea (4%)
- Management: Usually resolve within 3-7 days of continued use
When Circadin Side Effects Start
Side effects align with Circadin's absorption and peak plasma concentrations:
| Time After Dose | Pharmacological Stage | Likely Side Effects |
|---|---|---|
| 0-1 hour | Tablet dissolution begins | None typically |
| 1-2 hours | Initial absorption phase | Early drowsiness, mild headache |
| 2-4 hours | Approaching peak concentration | Nausea, dizziness onset |
Note: Morning grogginess (reported by 8% of users) manifests upon waking, ~6-8 hours post-dose.
Peak Side Effect Intensity
Most side effects reach maximum intensity during Circadin's peak action window:
Neurological Effects
- 3-5 hours post-dose
- Headache intensity peaks
- Maximum drowsiness
Gastrointestinal Effects
- 2-4 hours post-dose
- Nausea most pronounced
- Dry mouth noticeable
Other Effects
- 4-6 hours post-dose
- Vivid dreams occur
- Night sweats may start
How Long Side Effects Last
Duration varies by symptom type and individual metabolism:
| Side Effect | Average Duration | Factors Prolonging Effects |
|---|---|---|
| Drowsiness | 6-10 hours | Age >70, liver impairment |
| Headache | 4-8 hours | Dehydration, migraine history |
| Dizziness | 2-6 hours | Low blood pressure |
| Nausea | 1-3 hours | Taking without food |
Managing Side Effects
For Common Effects
| Symptom | Action | When to Seek Help |
|---|---|---|
| Morning drowsiness | Take Circadin earlier (2h before bedtime) | If persists >1 week |
| Headache | Hydrate + paracetamol | Severe/throbbing pain |
| Nausea | Take with light snack | Vomiting occurs |
Frequently Asked Questions
Why do I feel groggy the next morning?
Circadin's prolonged-release action maintains melatonin levels for 6-8 hours. This "hangover effect" (8% of users) usually adapts within 1-2 weeks as your body adjusts.
Can side effects worsen over time?
No. Most side effects peak during the first 3 days and improve with continued use. Worsening symptoms may indicate intolerance.
Do side effects depend on dose?
Yes. The 2mg dose is optimized - higher doses increase side effect risks without improving efficacy.
How does age affect side effects?
Adults over 70 may experience longer-lasting drowsiness due to slower metabolism. Dose adjustment isn't recommended.
Can I drink alcohol with Circadin?
Avoid. Alcohol exacerbates drowsiness and nausea, increasing fall risks.
Need Treatment for Jet Lag
If you're experiencing sleep difficulties, our UK-registered doctors can help determine if Circadin (Melatonin) Tablets is appropriate for your condition through a confidential online consultation.
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Medical Content Manager
Nabeel is a co-founder and medical content manager of Chemist Doctor. He works closely with our medical team to ensure the information is accurate and up-to-date.
Medical Doctor
Dr. Feroz is a GMC-registered doctor and a medical reviewer at Chemist Doctor. He oversees acute condition and urgent care guidance.
Medical Director
Usman is a co-founder and medical director of Chemist Doctor. He leads the organisation's strategic vision, bridging clinical and operational priorities.
Review Date: 29 October 2025
Next Review: 30 April 2026
Published on: 29 October 2025
Last Updated: 30 October 2025
