Peptide blends: what is in the vial and why the seller's label is not enough

What a blend is

A peptide blend is a product in which two or more peptides are pre-mixed in the same vial. The seller usually declares the components and their amounts in milligrams on the product page, but the declaration is the seller's own claim and has not been tested by an independent laboratory [21]. A review says the composition, dose and stacking practices of products from unregulated supply are uncertain [13].

According to Fimea, there is no reliable information on the content, quality and safety of products sold as peptides [1].

A studied combination medicine is a different thing. Its composition and doses are described, and it has been compared with placebo and with each component alone [4].

What is sold

The table lists the most common blends sold online. The contents column shows what sellers declare on their product pages (read 13 Oct 2026) [21]. The research status is as of October 2026. Where a study concerns only one component, this is stated [2, 4].

Read more: All blends | TB-500 | BPC-157 | GHK-Cu

What research says

We know of no published study in which a blend sold online was studied as a product or given to humans or animals. A review says many unapproved peptides show favourable results in animal models, but rigorous human safety data are scarce [18].

The only peptide combination we found that has been studied at scale in humans is CagriSema, that is cagrilintide plus semaglutide. The phase 3a REDEFINE 1 trial enrolled 3,417 adults without diabetes who had a body-mass index of at least 30, or at least 27 with a weight-related condition. Each substance was given at 2.4 mg [4].

At week 68, body weight had fallen by an average of 20.4% with the combination and 3.0% with placebo. Gastrointestinal adverse events, such as nausea, vomiting and diarrhoea, affected 79.6% of those on the combination and 39.9% of those on placebo. They were mostly transient and mild to moderate. The trial also had semaglutide-only and cagrilintide-only groups. The trial was funded by the manufacturer, Novo Nordisk [4].

A product sold online under the name CagriSema is not the trial product. According to the FDA page updated on 1 Oct 2026, cagrilintide cannot be used in compounding in the United States, is not a component of any FDA-approved drug, and has not been found safe and effective for any condition [5]. According to Novo Nordisk, the company applied to the FDA for a marketing authorisation on 18 Dec 2025, and no decision had been made by then [5, 22]. On 12 Oct 2026 the medicines data published by EMA contained no medicine with cagrilintide [6].

The combination of BPC-157 and TB-500 has been studied in rats. The cut and repaired Achilles tendons of 32 rats were treated for four weeks with BPC-157, TB-500, their combination or nothing. The combination gave no added benefit over either substance alone [2].

In humans we found only a retrospective chart review from one clinic. In it, four patients had received knee injections of BPC-157 and thymosin beta-4. Data were collected by phone interview, and there was no comparison group. The article does not say whether the substance was TB-500 [3].

Giving growth hormone-releasing hormone (GHRH) and a growth hormone-releasing peptide (GHRP) at the same time strongly increases growth hormone release. This was measured in healthy men with intravenous GHRH and GHRP-2 infusions, not with shop blends [12].

Five structural risks

These risks come from having several substances in one vial. They apply to every blend, whatever substances it contains [1, 13].

• Declared is not tested. Sellers usually declare the composition themselves [21], but the declaration does not show what is actually in the vial. In an analysis of TB500 and TB1000 products bought online, the content did not consistently match earlier descriptions [17], and according to Fimea an unauthorised product may contain a different substance than the packaging states [1].
• Fixed ratio. The amounts of the components cannot be adjusted separately: if you wanted less of one substance, you also get less of the others. For example, tirzepatide and vitamin B12 are sold as fixed-dose combinations whose potency and impurities have not been evaluated [14].
• The source of a harm cannot be identified. The FDA notes about adverse event reports for compounded semaglutide and tirzepatide that it is not always possible to tell whether a harm came from the drug or from other factors [5]. With several substances in one vial, there is no way to know which one caused the harm.
• The certificate of analysis may not cover every component. One overall purity figure does not show how much of each component there is. Components can also react with each other: a new impurity was found in tirzepatide-B12 products, formed by a reaction between tirzepatide and certain forms of B12 [14].
• The dose of a single substance cannot be calculated. When the ratio is unknown, the total amount in the vial does not tell you the amount of any one substance. A review notes that the dose of unregulated products is uncertain even for single substances [13].

Read more: Certificate of analysis (COA)

Claimed advantages and what is known

We know of no published studies of shop blends, and human studies of unapproved peptides are scarce in general [18]. So we found no research evidence for any benefit claimed for a blend.

In rats, BPC-157 plus TB-500 was no better than either substance alone [2]. A review of GLP-1 products found little justification for adding nutrients to injectable semaglutide or tirzepatide products [15].

Status in Finland

On 29 June 2026 Fimea warned about injectable peptides bought online. The warning gives BPC-157 and TB-500 among its example names. Fimea advises not ordering injectable peptides from online shops or through social media, and buying medicines only from legal pharmacies [1].

In the Finnish medicines list (230/2025), annex 1 A, which covers medicinal substance analogues and prohormones classified as medicines, names BPC 157, TB-500, GHK-Cu, CJC-1295, ipamorelin and Selank, among others. Under the list, a combination of substances that can be used to modify bodily functions through a pharmacological action is also regarded as a medicine [19].

On the WADA 2026 Prohibited List, BPC-157 falls under class S0, thymosin beta-4 and its derivatives (for example TB-500) under S2.3, and CJC-1295, ipamorelin and tesamorelin under growth hormone releasing factors (S2.2.4). These are prohibited at all times [20]. In a blend, one prohibited component is enough.

Read more: Peptides and the law

Why a COA cannot prove a blend is safe

Fimea advises not ordering injectable peptides from online shops or through social media [1]. A certificate of analysis (COA) does not change that. It is a laboratory report on one sample, and a seller's own COA does not prove quality by itself, because the content of products sold online does not always match the description [17].

For a certificate even to describe a blend's composition, it would need all the items below. Even with them, it does not show that the product is safe for people [1, 17].

• Identity of each component by mass spectrometry (MS), not just the blend name. The FDA points to difficulty characterising the active ingredient of peptides [7].
• The amount of each component in milligrams, so the ratio is visible. Without it, the dose of a single substance cannot be calculated [13].
• Impurities, including those formed by reactions between components. Such a reaction product was found in tirzepatide-B12 products [14].
• An endotoxin result for an injectable product. According to Fimea, impurities such as endotoxins that end up in a product during manufacture raise the risk of serious health hazards [1].
• The same batch as the vial. A certificate for another batch says nothing about this vial, because the content of products with the same name can vary [17].

Read more: How to read a COA