Edition 2: The Peptide Week, Oct. 31 to Nov. 5, 2026

Welcome to edition 2 of Best Peptides Today. This is a list of what we and our sister site, Best Peptides For, published from Oct. 31 to Nov. 5, 2026. Each line below is the piece’s own summary, and each piece links to its sources. Nothing here is new reporting.

A few things to keep in mind as you read. Compounded drugs are not FDA-approved. The HHS policy discussed below is interim, open for public comment, and not FDA approval. A warning letter is FDA’s position, not a ruling. Retatrutide and mazdutide are not FDA-approved as of Nov. 5, 2026, and CagriSema is not FDA-approved as of Nov. 4, 2026.

Best Peptides Today

Regulatory

• Alabama and Mississippi Boards Warned on Peptides Before HHS’s Interim Policy. How They Fit Is Unclear: Alabama and Mississippi boards told licensees not to compound non-FDA-approved or research-grade peptides. Both predate HHS’s policy; the fit is unclear.
• FDA Warning Letter Says Empower Pharmacy’s Compounded Semaglutide and Tirzepatide Appear to Be Copies: FDA says Empower’s compounded semaglutide and tirzepatide with added ingredients appear to be copies of approved drugs. It is FDA’s position, not a ruling.
• HHS Issues Interim Policy on Compounding Six Peptides, Including BPC-157 and TB-500: HHS says it does not intend to act against some 503A compounding of six peptides, under conditions. It is open for comment and is not FDA approval.
• FDA Warning Letters on Peptides: A Running Tracker: FDA warning letters that name peptide drugs, by category, with what FDA cited and a link to each letter. We found 149 since January 2025.
• Peptide Regulatory Changelog Since January 2025: A dated list of FDA, HHS, court and state-board actions on peptides and GLP-1 drugs since January 2025, each with its primary source.

News

• CagriSema Awaits an FDA Decision. Here Is What the Trials Show, and What Only Novo Has Said: Novo expects an FDA decision on CagriSema in Q4 2026. What is published, what only Novo has reported, and why the tirzepatide comparison is not simple.
• Retatrutide’s Phase 3 Results Are Now in NEJM and The Lancet. The Drug Is Still Unapproved: TRIUMPH-1 and TRIUMPH-2 show large weight loss with investigational retatrutide. Why Lilly’s figures and the journals’ differ, and what is not yet known.

Analysis

• Large Study Links GLP-1 Drugs to Lower Heart and Kidney Risk, and Higher Risk of Some Other Conditions: A study of about 71,000 adults with type 2 diabetes found 65 lower-risk and 53 higher-risk associations with GLP-1 drugs. It shows association, not cause.
• What FDA’s Warning Letters Say About ‘Research Use Only’ Peptides: FDA warning letters to five peptide sellers say ‘research use only’ labels did not change its conclusion. What FDA cited, and what a letter does not prove.
• What the BPC-157 Research Actually Shows: Animal Studies, a Few Small Human Reports: BPC-157 is in the news after HHS’s interim policy. Here is what the research covers in animals and in people, and what FDA says is missing.
• Where ‘More Serious Adverse Events’ With Tirzepatide Comes From: Three Trials, Mostly One: A meta-analysis found more serious adverse events with tirzepatide than semaglutide (RR 1.83). It rests on three trials, and one supplies most events.
• Semaglutide and Panic Attack Reports: What a New Study Found: Panic attack reports to FDA were higher with semaglutide, but authors say publicity may explain the pattern. An association cannot be excluded.
• Mazdutide’s US Phase 2 Trial: What a 179-Person Study Shows: Mazdutide’s only US trial with published results we found: a 179-person phase 2 study funded by Eli Lilly. What it found and what FDA has said.

Best Peptides For

Guides by goal

• Are Peptides Legal in the US? What FDA and HHS Say: Are peptides legal? It depends on the kind: approved, compounded, research-use-only, supplements. What FDA and HHS have said, with dates.
• Best Peptides for Cognitive Function: What Evidence Exists: Do semax or selank improve memory or focus? What FDA reviewed, what studies in people exist, how Russia’s registration differs from U.S. evidence.
• Best Peptides for Hair Growth: What the Evidence Shows: Do copper peptides like GHK-Cu or cosmetic peptide serums help hair loss? What small studies show, and the approved treatments that aren’t peptides.
• Best Peptides for Injury Recovery: Human Evidence: BPC-157 and TB-500 are popular for injuries, but what do studies in people show? Animal vs human evidence, regulatory status and what to ask a clinician.
• Best Peptides for Joint Pain: What Human Evidence Exists: Do semaglutide, collagen peptides or BPC-157 help knee osteoarthritis pain? What trials show, how good they are, regulatory status and risks.
• Best Peptides for Longevity: What the Evidence Shows: Do epitalon, MOTS-c or GHK-Cu extend lifespan? What human evidence exists (little), what comes only from mice, and where HHS and FDA disagree.
• Best Peptides for Muscle Growth: What the Evidence Shows: Do GH-releasing peptides like CJC-1295, ipamorelin, sermorelin and tesamorelin build muscle? Hormone markers vs real outcomes, status, and sport rules.
• Best Peptides for Sexual Health: What the Evidence Shows: Which peptides have evidence for low sexual desire? One approved drug, one with brain-scan studies, one with safety concerns, one that matched placebo.
• Best Peptides for Skin and Aging: What the Evidence Shows: Do collagen peptides, peptide creams or GHK-Cu work for skin aging? What the trials show, why the best studies disagree, and what FDA doesn’t review.
• Best Peptides for Type 2 Diabetes: What the Evidence Shows: Which peptide drugs are FDA-approved for type 2 diabetes, and what trials found on blood sugar, heart and kidneys. Not every one protects the heart.
• Best Peptides for Weight Loss: What the Evidence Shows: Which peptides have evidence for weight loss? FDA-approved vs investigational, with the trials and the criteria. Educational, not medical advice.
• Compounded GLP-1 Drugs: What FDA Says: What FDA says about compounded semaglutide and tirzepatide: not FDA-approved, limits on copies of approved drugs, quality and dosing concerns.
• GLP-1 Muscle Loss: What the Data Show: How much muscle do GLP-1 drugs cost? DXA and MRI data, two 2026 reviews that disagree, what is still unknown, and drugs in trials to protect muscle.
• Research Use Only Peptides: What FDA Says the Label Means: ‘Research use only’ is not a legal category. What FDA said in 2026 warning letters, what it treats as proof of human use, and what a letter doesn’t prove.

Peptide guides

• BPC-157: What the Research Shows and What It Doesn’t: BPC-157 is not FDA-approved. What human and animal studies show, the Oct. 30, 2026 HHS enforcement policy, what it is not, and known risks.
• Bremelanotide: One Approved Use, a Modest Effect: Bremelanotide (Vyleesi) is FDA-approved only for premenopausal women with acquired, generalized HSDD. What trials showed, the risks and what isn’t proven.
• Collagen Peptides: Skin and Joint Evidence, and Its Limits: Do oral collagen peptides help skin or knees? Pooled trials look positive, but one meta-analysis found no effect in higher-quality studies. What we know.
• GHK-Cu: What the Research Shows and Where It Stands: GHK-Cu is not an FDA-approved drug. What human and animal studies show, how FDA treats injectable vs non-injectable forms, and what hasn’t been tested.
• Liraglutide: Saxenda, Victoza, Trial Results and Shortages: Liraglutide is FDA-approved as Saxenda and Victoza. What SCALE and LEADER found, the boxed warning, the shortage list by product, and compounded versions.
• Retatrutide: What Published Trials Show, and Its Status: Retatrutide is investigational and not FDA-approved. What the published phase 3 trials found, why 28% and 25% differ, the risks seen, and its FDA status.
• Selank: Is It Approved? What the Evidence Actually Shows: Selank is not FDA-approved or in HHS’s peptide policy. The human and animal studies that exist, FDA’s safety concerns, and how it differs from semax.
• Semaglutide: Trial Evidence, Risks and Compounded Versions: What semaglutide (Wegovy, Ozempic, Rybelsus) did in major trials, its boxed warning and side effects, and where compounded versions stand with FDA.
• Semax: What the Evidence Shows and Where It Stands: Semax is not FDA-approved. What FDA reviewed, what studies in people exist, the HHS interim policy’s narrow coverage, and the safety questions.
• Tesamorelin: One Approved Use, and What It Doesn’t Cover: Tesamorelin (Egrifta) is FDA-approved to reduce abdominal fat in adults with HIV and lipodystrophy only. What the trials show, risks and what isn’t proven.
• Tirzepatide: Trial Evidence, Risks and Compounded Versions: What tirzepatide (Zepbound, Mounjaro) did in major trials, what happens to lean mass, its boxed warning, and where compounded versions stand with FDA.

Comparisons

• BPC-157 vs TB-500: What the Evidence Shows: BPC-157 and TB-500 are sometimes marketed together. What studies exist for each, how HHS’s Oct. 30 policy treats them, and why they aren’t the same.
• Semaglutide vs Liraglutide: What the Head-to-Head Shows: One head-to-head trial, two FDA-approved GLP-1 drugs. How semaglutide and liraglutide compare on weight, labels, heart trials, safety and supply.
• Semaglutide vs Tirzepatide: What Head-to-Head Data Show: Two head-to-head trials, two FDA-approved drugs. How semaglutide and tirzepatide compare on weight, heart, sleep apnea and safety, and what can’t be.
• Tirzepatide vs Retatrutide: Approved vs Investigational: Tirzepatide is FDA-approved; retatrutide is still experimental. What trials show for each, why they can’t be ranked yet, and their FDA status.
• Wegovy vs Ozempic: Same Drug, Different Labels: Wegovy and Ozempic both contain semaglutide but have different FDA labels. What each is approved for, which trials fit each, and what that means.
• Zepbound vs Mounjaro: Same Drug, Different Labels: Zepbound and Mounjaro both contain tirzepatide but have different FDA labels. What each is approved for, the trials that fit each, and the warnings.

Reference

• Peptide Glossary: Plain-English Definitions: What a peptide is, and what FDA-approved, compounded, investigational and other terms mean, with definitions and sources for each regulatory claim.
• How We Rate Peptides: What “Best” Means: How Best Peptides For ranks peptides by the strength of the evidence, what our evidence types and status labels mean, and what a ranking is not.

Dates to watch

• Public comments on the HHS interim policy close at 11:59 p.m. Eastern on Nov. 13, 2026, according to Regulations.gov.
• Novo Nordisk says it expects a US regulatory decision on CagriSema in the fourth quarter of 2026. See our CagriSema report.

Edition 1 is here. U.S. regulatory status checked Nov. 5, 2026.