Christine
The products are great and fast…
The products are great and fast shipping.

We are a trusted research supplier committed to delivering high-quality products for laboratories, academic institutions, and independent researchers. Every product is validated through rigorous third-party testing and accompanied by advanced Certificates of Analysis (COAs), ensuring accuracy, reliability, and full transparency. Our dedicated customer support team and fast, dependable shipping provide a seamless experience from order to delivery. As a leading provider in the research field, we uphold strict standards of consistency, uncompromising quality, and exceptional service—empowering you to advance your work with complete confidence.
Sigma (sigmapeptides.com) has 36 customer reviews on Five Star Index, with an average rating of 4.5 out of 5.
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Christine
The products are great and fast shipping.
James F.
No direction on how to use or dilute. And no response to email about it.
C.
THIS WEBSITE USES THE NAME SIGMA SINCE OTHER REPUTABLE SITES HAVE SIMILAR NAME ,BUT THE PRODUCTS ARE FAKE. Their retatrutide is false, it doesn't work, the worst part is not knowing what you are putting in your body. They are from Colombia, and they had a facebook page with some good reviews, probably from themselves, AND NOW THE PAGE IS CLOSED. Do not buy anything from them. AND they dont reply emails.
Response from SigmaMay 10, 2026
Thank you for the review, but the claims here don't match any of our records and warrant a direct response. 1. We are a US-based company and ship exclusively from US fulfillment centers. Domestic delivery is 2-3 business days, which would be physically impossible from Colombia. Our shipping records, tracking numbers are all verifiable. 2. Every product we ship has a Certificate of Analysis (COA) displayed publicly on each product page. These are third-party HPLC test results, not internal claims. 3. We have a real, monitored support inbox at [email protected] that responds within 24 hours, often the same day. We are happy to look up any order under this name and address it directly. If you have a genuine order with us, please share your order number (privately or via support) and we will investigate immediately. If you don't have one, we'd ask you to consider that posting unverified claims about a business you have not transacted with is what Trustpilot's policy considers a violation. — Sigma Peptides Team
Jenn
After checking out, the amount charged to my card was DOUBLE! Multiple emails linked a "respond" to email, but would then bounce back. I was able to report and cancel the transaction to my financial institution while it was still pending - but it took longer to try and tell the company to terminate it. Was also bombed with emails multiple times a day - in both English and Spanish versions. Be cautious of this company.
Response from SigmaMay 10, 2026
Hi Jenn — thank you for taking the time to leave feedback. We take charge discrepancies seriously and want to look into this directly. A few clarifications that might help: 1. We do not double-charge customers. If you saw two pending charges on your card, this is most likely a temporary authorization hold (common with high-risk processors) that is automatically released within 3-5 business days. Only one charge is ever captured per order. 2. If your discount code didn't apply at checkout, the displayed total may have looked different from the final charge. We're happy to verify this against your order. 3. Our reply email address ([email protected]) is monitored daily and we respond within 24 hours. If your email bounced, please reach out again — something may have been flagged in transit. 4. Email frequency: we send one promotional email per campaign in both English and Spanish for our bilingual customer base. You can adjust your preferences or unsubscribe via the footer of any email at any time. Please share your order number (via [email protected]) and we will personally walk through the transaction with you and resolve any discrepancy. If there was an actual double charge, we will refund it immediately. — Sigma Peptides Team