The short answer
Melatonin may add to orphenadrine-related drowsiness or impaired alertness. Review the exact product and other sedating medicines before adding it; this combination’s risk has not been measured directly.
What this answer covers
Oral melatonin; dose and release form vary.
- Supplement or preparation
- Melatonin
- Medication ingredient
- orphenadrine
The medicine can affect alertness
Anticholinergic effects, dizziness, drowsiness and impaired driving; tachycardia and urinary retention precautions. These medication warnings do not supply a supplement-specific adverse-event rate.
What the supplement evidence shows
In a small crossover study, melatonin increased subjective sleepiness but did not worsen the overall objective driving-test result. This distinction matters: feeling sleepy and measured performance are different outcomes, and the study did not test this combination.
Keep the preparation and outcome clear
Dose, formulation and other ingredients matter. No exact-pair trial identified here established how much impairment would increase, and a negative result for one product alone does not prove the combination safe.
Review co-use and daily activities
Discuss the product with the prescriber or pharmacist before adding it. Avoid driving while drowsy or dizzy. No exact protective spacing interval was established, and a supplement should not be used to counteract medication impairment.
Evidence and practical considerations
Side effects & toxicity
Conditional additive-alertness precaution from medication-specific effects and supplement guidance; direct pair harm, respiratory depression rate and protective spacing not established.
- Exact scope
- Oral melatonin; dose and release form vary. with Oral orphenadrine citrate extended-release tablets; fixed aspirin/caffeine combination distinguished.
- Medication form and route
- oral medication; oral supplement
What remains uncertain
- No unmeasured pair incidence, blanket class transfer or arbitrary spacing interval.
Factors that may matter: Preparation; Dose; Other medicines; Organ function.
Read the supporting source summaries
Source 1: current product label
dailymed.nlm.nih.gov · Source check Sep 10, 2026
Population: People prescribed orphenadrine
Anticholinergic effects, dizziness, drowsiness and impaired driving; tachycardia and urinary retention precautions.
How this applies: Exact orphenadrine RxCUI 7715 IN, with stated salt/formulation/route bridge.
No exact supplement-combination incidence or validated protective spacing; salt, route and release form limits apply.
Source 2: Federal supplement guidance
nccih.nih.gov · Source check Sep 10, 2026
Population: People considering the named botanical or supplement.
Sleepiness is a possible effect. Older people may have prolonged daytime drowsiness; commercial products and long-term safety data vary.
How this applies: Interpreted for orphenadrine only within the stated exact preparation and endpoint limits.
No exact orphenadrine combination trial; original population, preparation and endpoint restrictions apply. No quantified pair risk or protective dose interval.
Source 3: Original human study
pubmed.ncbi.nlm.nih.gov · Source check Sep 10, 2026
Population: Twenty healthy adults in a crossover.
Subjective sleepiness increased after a prolonged task, but the overall objective driving-test battery did not show impairment.
How this applies: Interpreted for orphenadrine only within the stated exact preparation and endpoint limits.
No exact orphenadrine combination trial; original population, preparation and endpoint restrictions apply. No quantified pair risk or protective dose interval.
Research assessment: · Open full citations ↗
Review and change history
- Publication status
- Published research summary
- Clinical review
- Not yet recorded
| Date | Update |
|---|---|
| Research summary published | |
| Article prepared | |
| Prepared exact orphenadrine article with formulation-specific evidence and uncertainty. |
Article revision: 2fb23e2a9299a424
This guide brings together the evidence records used by our interaction checker. Each finding retains its own preparation limits, research date, and source summaries.
Full citations require verification. Reading this answer and the source summaries does not.
Taking other supplements or medications?
Use the checker to explore your other combinations. Ask a pharmacist to review the exact products, amounts and medical conditions in your complete list.
Open the interaction checkerInformation, not medical advice. Do not change prescribed treatment based on this guide.