What are peptides, really?
Peptides are short chains of amino acids — smaller than proteins but built from the same building blocks. The human body produces thousands of them, many of which act as signaling molecules: telling cells to release growth hormone, repair tissue, modulate inflammation, regulate appetite.
Therapeutic peptides aim to amplify or restore these natural signaling pathways. Many are compounded by 503A pharmacies under physician oversight rather than mass-manufactured as FDA-approved drugs, which means clinical evidence is uneven across products.
The peptides with the strongest evidence base
A few peptides have substantial mechanistic and clinical data:
- CJC-1295 + Ipamorelin — a growth hormone-releasing hormone analog plus a ghrelin mimetic. Stimulates pulsatile GH release. Human studies confirm increased IGF-1 and GH secretion.[1]
- Sermorelin — GHRH analog, FDA-approved for pediatric GH deficiency. Off-label adult use has decades of clinical use though limited large RCTs.[2]
- Tesamorelin — FDA-approved for HIV-associated lipodystrophy. Reduces visceral adipose tissue in human trials.[3]
- Semaglutide / Tirzepatide — technically peptide-based GLP-1 analogs with extensive RCT data (covered in our GLP-1 article).
The peptides with mostly preclinical data
Several popular peptides have promising animal data but limited rigorous human trials:
- BPC-157 — strong rodent data for tendon/ligament healing, gut repair, anti-inflammatory effects. Human RCTs are limited; reported clinical experience is favorable but anecdotal-leaning.[4]
- TB-500 (Thymosin Beta-4) — animal data for tissue repair; very limited human evidence.
- PT-141 (Bremelanotide) — FDA-approved for hypoactive sexual desire disorder in women; some male use is off-label.
Why physician oversight matters
Peptides are biologically active compounds with real physiologic effects — which means they can have real adverse effects when misused. CJC-1295/ipamorelin can affect glucose tolerance. Tesamorelin requires monitoring of IGF-1 and glucose. BPC-157 has insufficient long-term safety data in humans.
A responsible peptide protocol includes baseline labs appropriate to the peptide (typically a metabolic panel, IGF-1, fasting glucose/insulin, and a CBC), defined treatment goals, and periodic follow-up bloodwork to track both benefit and any unintended changes. This is not "biohacker" territory — it is the same standard of care any prescription requires.
What to do with this information
If peptide therapy interests you, the right starting point is a physician who can distinguish well-supported peptides from poorly-supported ones for your specific goals — and who will order appropriate labs before and during therapy. Marketing claims and clinical evidence are different things; a thoughtful clinician helps you tell them apart.
