Peptide Sciences shuts down; notice gives no reason

Peptide Sciences, one of the best-known online sellers of “research use only” peptides, took down its storefront on March 6, 2026. In its place, peptidesciences.com showed a short notice. The Peptide List reported it appeared at about 2:00 PM Eastern that day. As preserved in an Internet Archive capture from March 8, it read:

“After careful consideration, Peptide Sciences has made the decision to voluntarily shut down operations and discontinue the sale of our research products. We are deeply grateful for your trust and support. Thank you for being part of the Peptide Sciences community.”

How the notice changed

TitrateLab reviewed nine Internet Archive captures from March 8 to September 8 and found two later versions:

• By March 21: a warning that anyone claiming to be Peptide Sciences or a successor, or claiming to sell its products, is “fraudulent, unauthorized, and have absolutely no affiliation with our company.” (The Internet Archive’s March 22 capture shows the same wording.)
• By April 15: wording asserting the company “retains all rights, title, and interest in and to its name, brand, trademarks, intellectual property, and associated goodwill.”

No version gives a reason for closing or says anything about open orders or refunds.

What is not known

Why. The company has not said. TitrateLab searched fda.gov and justice.gov on October 11 and found no warning letter, enforcement action or charge naming the company. Some coverage has claimed a 2023 FDA letter; we have not located it on fda.gov and treat it as unconfirmed.

Timing context. The closure came seven days after HHS Secretary Kennedy’s February 27 podcast remarks on peptides (report) and about five weeks after Science.bio closed (report). No public record we found links the closure to either event.

Sites using the name

A site at peptidesciencesinc.com now says the Peptide Sciences name continues there. That conflicts with the original notice’s warning about successors. We have not established who runs it and make no claim about it. Buyers who see a certificate from any seller using the name can check whether it verifies on the issuing lab’s own system. See how to verify a COA.

We keep a dated status log for the domain.