Updated October 2026 · 8 vendors ranked

Peptide Partners FDA Warning Letter (2026): What It Says and Vendors to Compare

FDA sent Peptide Partners a warning letter dated August 24, 2026, citing health claims for GLP-1-class products and the sale of reconstitution solution. What it says, what it means for buyers, and eight vendors to compare.

By Carsten Jessen
Updated Oct 7, 2026 · 3 min read
Reader-supported: we may earn a commission from links on this page. How we make money · How we rank

The 8 best, ranked

#1
Rank 1
1
American Peptides
americanpeptides.us
9.1
/10
American Peptides
Best overallamericanpeptides.us · Verified Sep 2026
Why it’s here: Lets you pull up the COA for the lot number on your vial (126 lot-matched certificates on file) and names its testing lab, Bioviridian, on its homepage.
Payment
Visa, MC, Amex, Discover, ACH, crypto
Ships from
Shreveport, LA (US)
Testing lab
Bioviridian (homepage; not on COA page)
COA per batch
Yes (126 lot-matched, lot lookup)
- Pro: A lot-number lookup tool and 126 lot-matched certificates on file, per its verify page
- Pro: Names a testing lab on its homepage: Bioviridian (College Station, TX), which runs its own public COA search
9.1/10
Overall
3.0 (14) Trustpilot
Visit American Peptides Read American Peptides review
#2
Rank 2
2
NextGenPeps
nextgenpeps.com
8.8
/10
NextGenPeps
Labs named on every COAnextgenpeps.com · Verified Sep 2026
Why it’s here: Best for cOAs with named labs and endotoxin data. Names both of its labs on its own site: Janoshik and BioRegen, each of which offers public report verification.
Payment
Visa, MC, Amex, Discover, PayPal, Apple Pay
Ships from
California (US), US only
Testing lab
Janoshik, BioRegen
COA per batch
Dated per test; lot not shown in library
- Pro: Names both of its labs on its own site: Janoshik and BioRegen, each of which offers public report verification
- Pro: COA library of about 49 entries, each dated (July 2025 to June 2026) with a purity result, and endotoxin results on some batches
8.8/10
Overall
3.1 (21) Trustpilot
Visit NextGenPeps Read NextGenPeps review
#3
Rank 3
3
PSPeptides
pspeptides.com
8.5
/10
PSPeptides
pspeptides.com · Verified Sep 2026
Why it’s here: Best for payment flexibility and fast US shipping. Certifications page covers about 60 products, with COAs dated by month and a test ID on each file.
Payment
Cards, Apple/Google Pay, Zelle, Cash App, BNPL
Ships from
New Jersey (US)
Testing lab
North American Diagnostics (on COA we opened)
COA per batch
Dated by month; batch on PDF
- Pro: Certifications page covers about 60 products, with COAs dated by month and a test ID on each file
- Pro: The COA we opened was issued by a named lab (North American Diagnostics) and included a batch number and method
8.5/10
Overall
4.2 (175) Trustpilot
Visit PSPeptides
10% off
CHECKED
Read PSPeptides review
Rank 4
4
Ascension Peptides
ascensionpeptides.com
8.1
/10
Ascension Peptides
ascensionpeptides.com · Verified Sep 2026
Why it’s here: Best for searching COAs by batch/lot. COA library with 85 records, searchable by product, SKU, batch/lot, purity and date.
Payment
Cards (per third-party review; not verified)
Ships from
US (address not on site), US only
Testing lab
Kovera Labs, MZ Biolabs (product pages)
COA per batch
Yes (85 records, searchable by lot)
- Pro: COA library with 85 records, searchable by product, SKU, batch/lot, purity and date
- Pro: Two independent reviews trace its certificates to MZ Biolabs (Tucson, AZ), using HPLC-UV-MS
8.1/10
Overall
No Trustpilot reviews yet
Visit Ascension Peptides
50% off first order
AFFILIATE50OFF
Read Ascension Peptides review
Rank 5
5
Peptide Plugs
peptideplugs.com
7.5
/10
Peptide Plugs
peptideplugs.com · Verified Sep 2026
Why it’s here: Best for checking a COA at the lab itself. COA page lists 117 certificates across 62 products, each dated with purity and measured content.
Payment
Credit card
Ships from
Liberty Hill, TX (US), US only
Testing lab
Freedom Diagnostics
COA per batch
Yes (117 dated; lot on product pages)
- Pro: COA page lists 117 certificates across 62 products, each dated with purity and measured content
- Pro: Names its lab, Freedom Diagnostics, on its site; product pages show a lot, an accession code and a link to the lab's own COA search
7.5/10
Overall
No Trustpilot reviews yet
Visit Peptide Plugs Read Peptide Plugs review
Rank 6
6
Swiss Chems
swisschems.is
6.5
/10
Swiss Chems
swisschems.is · Verified Sep 2026
Why it’s here: Best for wide catalog beyond peptides. The longest track record of the six: its site says it was established in 2018.
Payment
Mastercard, ACH/Zelle via 4Square, crypto
Ships from
Not stated (site says US-based)
Testing lab
Janoshik (per FAQ); not shown on results page
COA per batch
Yes (batch codes in report files)
- Pro: The longest track record of the six: its site says it was established in 2018
- Pro: A test-results page with 60 reports, many dated September 2026, with batch codes in the file names
6.5/10
Overall
No Trustpilot reviews yet
Visit Swiss Chems Read Swiss Chems review
Rank 7
7
Licensed Peptides
licensedpeptides.com
7.4
/10
Licensed Peptides
licensedpeptides.com · Verified Sep 2026
Why it’s here: Best for endotoxin reports, 2-day shipping. Names its labs, Vanguard Laboratory and Ethos Analytics, with ISO/IEC 17025 accreditation numbers on its own site.
Payment
ACH/e-check in terms; others not confirmed
Ships from
US (Boca Raton, FL address published), US only
Testing lab
Vanguard Laboratory, Ethos Analytics
COA per batch
Indexed by lot; some lots appear reused
- Pro: Names its labs, Vanguard Laboratory and Ethos Analytics, with ISO/IEC 17025 accreditation numbers on its own site
- Pro: Publishes endotoxin (LAL) reports alongside purity reports, indexed by lot
7.4/10
Overall
No Trustpilot reviews yet
Visit Licensed Peptides
5% off
Affiliate5
Read Licensed Peptides review
Rank 8
8
Alpha Pro Peptides
alphapropeptides.com
6.3
/10
Alpha Pro Peptides
alphapropeptides.com · Verified Sep 2026
Why it’s here: Best for checking lot, purity and net content. Testing page lists each COA with a lot ID, report date, purity and measured net content.
Payment
Cards except Mastercard, Apple Pay, Google Pay
Ships from
US (address not published), US only
Testing lab
Freedom Diagnostics (on COAs)
COA per batch
Yes (lot ID, date, purity, net content)
- Pro: Testing page lists each COA with a lot ID, report date, purity and measured net content
- Pro: The COA we opened was issued by Freedom Diagnostics, and an independent review matched 35 reports to lab-hosted copies
6.3/10
Overall
No Trustpilot reviews yet
Visit Alpha Pro Peptides Read Alpha Pro Peptides review

What each one looks like

American Peptidesamericanpeptides.us · captured Sep 2026
NextGenPepsnextgenpeps.com · captured Sep 2026
PSPeptidespspeptides.com · captured Sep 2026
Ascension Peptidesascensionpeptides.com · captured Sep 2026
Peptide Plugspeptideplugs.com · captured Sep 2026
Swiss Chemsswisschems.is · captured Sep 2026
Licensed Peptideslicensedpeptides.com · captured Sep 2026
Alpha Pro Peptidesalphapropeptides.com · captured Sep 2026

FDA sent Peptide Partners a warning letter dated August 24, 2026. It cites health claims on the company's website and its sale of a reconstitution solution alongside injectable peptides (FDA letter). A warning letter isn't a closure, and we couldn't confirm the company's status on September 27, 2026. If you're comparing options, Peptide Plugs (8.1/10) and NextGenPeps (8.0) score highest of the eight vendors we review.

Notice: Research peptides are sold for in-vitro laboratory research only. They are not FDA-approved, not for human or animal consumption, and this page is not medical advice.

What the letter says

The letter went to Peptide Partners LLC in Sarasota, Florida, about its website peptide.partners. It was one of five dated August 24 and posted around September 1, 2026 (JackedForums summary).

Products named: semaglutide, tirzepatide and retatrutide (sold under "GLP" names), SS-31, tesamorelin, PT-141 and a reconstitution solution (bacteriostatic water).
Health claims: FDA quoted site copy saying, for example, that tirzepatide is "effective in lowering blood sugar and reducing weight" and that SS-31 "could be a potential treatment to protect the retina."
Supplies as evidence: FDA said selling a solvent for the injectable products provided "the means to prepare an injectable drug for human administration," which undercut the "research use only" label.
Deadline: the company was asked to respond in writing within 15 business days.

The same pattern shows up in the other 2025-2026 letters in our shutdown timeline: labels don't protect a seller whose marketing or supplies point to human use.

What it means for buyers

It's a regulatory warning, not a verdict on product quality. The letter says nothing about purity or testing either way.
Vendors in this market can change or close quickly. Our shutdown timeline shows how often it has happened since 2025.
Health claims are a signal to note. Our reviews flag vendors that publish dosing guides or disease claims, because that's what FDA cites.

Eight vendors to compare

Listed in our editors' order, which isn't sorted by score. Checked September 26, 2026 (Licensed Peptides September 28, 2026). GLP-1-class products made up most of the items named in the letter.

Vendor	Score	Best for	Lab named on site	Ships to	Our code
American Peptides	9.1	Lot lookup, international	Homepage only (Bioviridian)	US and 215 countries	None
NextGenPeps	8.8	Named labs, PayPal	Yes (Janoshik, BioRegen)	US and territories	None
PSPeptides	8.5	Speed, payment range	No (on PDFs)	US, Canada, EU, UK, Australia	CHECKED (10%)
Ascension Peptides	8.1	Lot search, first-order price	Product pages	US only	AFFILIATE50OFF (50% first order)
Peptide Plugs	7.5	Lab-side verification	Yes (Freedom Diagnostics)	US only	None
Swiss Chems	6.5	Long history, overnight shipping	FAQ only (Janoshik)	US and international	None
Licensed Peptides	7.4	Endotoxin reports, 2-day shipping	Yes (Vanguard, Ethos)	US only	Affiliate5 (5%)
Alpha Pro Peptides	6.3	Net content per lot	No (on PDFs)	US only	None

Best documented testing: Peptide Plugs and NextGenPeps.
Note on FDA history: Swiss Chems received its own FDA letter in December 2024, and PSPeptides publishes human dosing guides on its blog. Both are disclosed in their reviews.

Full ratings: best peptide vendors in the USA. Related: FDA peptide regulation in 2026 · peptide regulatory news · Peptide Sciences alternatives

FAQ

Frequently asked questions

Did Peptide Partners get an FDA warning letter?

Yes. FDA sent Peptide Partners LLC of Sarasota, Florida a warning letter dated August 24, 2026 (reference 735063). It was posted publicly around September 1, 2026.

What did the FDA letter cite?

Health claims on its website for products including semaglutide, tirzepatide, retatrutide and SS-31, and the sale of a reconstitution solution (bacteriostatic water) alongside injectable peptides, which FDA said showed intended human use despite 'research use only' labels.

Is Peptide Partners shut down?

We couldn't confirm either way on September 27, 2026. A warning letter isn't a shutdown order; it asks the company to respond within 15 business days. Check its current status yourself before ordering.

What is the best Peptide Partners alternative?

On our transparency method, Peptide Plugs (8.1) and NextGenPeps (8.0) score highest of the eight vendors we review. GLP-1-class products were most of what the letter named.

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