Beginner's Guide to Peptides

Peptides are short chains of amino acids — the same building blocks that make up proteins. The distinction between a peptide and a protein is primarily one of size: peptides are generally defined as chains of fewer than 50 amino acids, while proteins are longer. In practice, many research peptides are 5–30 amino acids in length.

Peptides occur naturally throughout the body, where they function as hormones (insulin is a peptide hormone), neurotransmitters, growth factors, and signaling molecules. The research peptides covered on this site are either synthetic versions of naturally occurring peptides or novel sequences designed to interact with specific biological targets.

Because peptides are made of amino acids, they are broken down by digestive enzymes when taken orally — which is why most research peptides are administered by subcutaneous injection rather than orally. A few peptides (like Semax) can be administered intranasally, and some (like BPC-157) have been studied in oral form due to their unusual stability.

Research peptides span multiple therapeutic areas. The major categories covered on this site include:

• Healing & Recovery: BPC-157, TB-500, and similar peptides studied for tissue repair, wound healing, and anti-inflammatory effects.
• Metabolic & Weight Loss: GLP-1 receptor agonists (semaglutide, tirzepatide, retatrutide) and related compounds studied for metabolic regulation and weight management.
• Growth Hormone Secretagogues: Ipamorelin, CJC-1295, GHRP-2, and similar peptides that stimulate GH release via GHRH or ghrelin receptors.
• Brain Health & Nootropics: Semax, Selank, DSIP, and similar peptides studied for cognitive enhancement, neuroprotection, and sleep regulation.
• Longevity & Mitochondrial: SS-31, Epitalon, and similar peptides studied for anti-aging, mitochondrial function, and cellular health.
• Hormonal & Sexual Health: PT-141 (Bremelanotide) and similar peptides acting on melanocortin or other hormonal pathways.

Research peptides are supplied as lyophilized (freeze-dried) powder in sealed vials. Before use, the powder must be dissolved in a liquid diluent — a process called reconstitution.

The standard diluent is bacteriostatic water (BAC water), which contains 0.9% benzyl alcohol as a preservative. This allows the reconstituted vial to be used multiple times over several weeks without bacterial contamination.

The volume of BAC water you add determines the concentration of the resulting solution. For example, adding 2 mL to a 5 mg vial yields a concentration of 2.5 mg/mL. Adding 3 mL yields 1.67 mg/mL. The concentration then determines the injection volume for each dose.

The standard syringe for subcutaneous peptide injections is the U-100 insulin syringe. These syringes are calibrated for U-100 insulin (100 units per mL), meaning each unit on the syringe equals 0.01 mL.

To convert your calculated injection volume (in mL) to syringe units: multiply by 100. For example, 0.15 mL = 15 units on a U-100 syringe.

Common U-100 syringe sizes are 0.3 mL (30 units), 0.5 mL (50 units), and 1.0 mL (100 units). For most peptide doses, a 0.3 mL or 0.5 mL syringe is sufficient.

Proper storage is critical for maintaining peptide stability and potency.

• Lyophilized (unreconstituted): Store at −20°C (−4°F) in dry, dark conditions. Properly stored lyophilized peptides can remain stable for 12–24 months.
• Reconstituted: Refrigerate at 2–8°C (35.6–46.4°F), protected from light. Most reconstituted peptides remain stable for 14–30 days. Do not freeze reconstituted peptides.
• Avoid freeze-thaw cycles: Repeated freezing and thawing degrades peptide structure. Once reconstituted, keep refrigerated and do not refreeze.
• Protect from light: UV light can degrade peptide bonds. Store vials in their original packaging or in a dark location.

Research peptides vary widely in their evidence base, safety profiles, and regulatory status. Before beginning any research protocol, consider the following:

• Evidence quality varies: Some peptides (semaglutide, tirzepatide, PT-141) have extensive human clinical trial data. Others (BPC-157, TB-500) have primarily preclinical data. Calibrate your confidence accordingly.
• Consult a healthcare professional: Nothing on this site is medical advice. Always consult a qualified healthcare provider before making decisions about peptides.
• Source matters: Peptide purity and quality vary significantly between suppliers. Research-grade peptides should have certificates of analysis (COA) from independent third-party labs.
• Sterile technique: Use new sterile syringes for each injection. Dispose of used syringes in a sharps container. Never share injection equipment.
• WADA status: Many peptides are prohibited by the World Anti-Doping Agency (WADA). If you compete in any sport governed by WADA, check the prohibited list before use.