At a glance · 10 Nov 2026
- Suppliers tracked
- 35 list Melatonin; 28 with a listing on sale (36 listings confirmed in stock)
- Sizes on sale
- Suppliers on this page sell Melatonin in 10 mg vials. Some also sell packs of 10 vials, compared per mg of the whole pack rather than against single vials. Other forms on sale (capsules) are different products and are not compared per mg with vials. How prices are compared
- Price per mg, single vials (GBP)
- £1.98/mg to £10.90/mg, median £2.90/mg, across 10 single-vial listings from 9 suppliers
- Test certificates
- Not yet collected by PepFinder for Melatonin; check each supplier's site. How to read a COA
What Melatonin is
Melatonin is a hormone made by the pineal gland from tryptophan, via serotonin, that signals darkness to the body clock. It is not a peptide, but peptide stores sell it in 10 mg and 20 mg capsules, drops and occasionally vials alongside sleep peptides such as DSIP. Meta-analyses find it shortens the time taken to fall asleep by a few minutes and adds a few minutes of sleep, it helps jet lag when timed to the destination bedtime, and it is a prescription-only medicine in the UK but a freely sold supplement in the US. Read the full Melatonin guide, with the published research and references.
Before you choose a Melatonin supplier
Price per mg is only half the comparison. Check that the supplier publishes a certificate of analysis for the batch it is selling, ideally from an independent laboratory, and that the certificate confirms identity as well as purity: our guide on how to read a COA shows what to look for. A price far below the rest of the list is more often a warning than a bargain; peptide prices explained sets out why.
For what Melatonin is and what published studies have found, see our Melatonin guide. Handling questions are covered in how to store peptides, and the peptide calculator converts a vial size and water volume into concentration and syringe units. Rules on buying and importing differ by country: see legal status by country, or narrow this list to your region above.
Checking a Melatonin certificate of analysis
- The certificate names a laboratory you can find independently, and ideally one with no stake in the result.
- It carries a batch or lot number that matches the product page or the vial label, and a test date.
- It confirms identity by mass spectrometry, not only purity by HPLC. Purity alone does not show the vial contains Melatonin.
- It includes the chromatogram and mass spectrum, not just a summary table.
- Where the laboratory offers online verification of its reports, the report number checks out.
Red flags
- No certificates at all, or certificates available only “on request”.
- The same certificate used for several products or several years of stock.
- Payment only by cryptocurrency or bank transfer, with a discount for paying that way.
- A price far below every other supplier on this page.
- No way to contact the store other than a web form.
- Vials labelled only with a code rather than the product name and strength.
How to spot a fake peptide supplier explains each of these in more detail, and third-party peptide testing covers what independent results can and cannot prove.
Vials, capsules and pre-mixed products
Most research peptides are sold as freeze-dried (lyophilised) powder in sealed vials, which is mixed with a diluent such as bacteriostatic water before use in the lab. Some suppliers also sell pre-mixed solutions, nasal sprays or capsules under the same name. These are different products with different stability and dosing, so compare price per mg only between the same form, and check which form a listing is before comparing it with the rest of the table.
How this list is built: suppliers appear because they list Melatonin on their own website, read by our catalogue checks; nobody pays to be included or to move up. Ranking is by PepFinder Score, with stores that have nothing on sale after those that do. Prices, sizes and stock are as each site listed them when checked and may have changed.
