Question 1

What is a peptide?

Accepted Answer

A peptide is a short chain of amino acids, typically between 2 and 50 amino acids long. Unlike larger proteins, peptides act as highly specific signaling molecules in the body, binding to receptors to trigger distinct biological responses like tissue repair, hormone release, or fat metabolism.

Question 2

How do peptides work in the body?

Accepted Answer

Peptides work by mimicking naturally occurring signals. For example, GLP-1 agonists mimic the hormone that tells your brain you are full, while growth hormone secretagogues signal your pituitary gland to release more natural growth hormone. They essentially 'turn on' or 'turn off' specific cellular processes.

Question 3

Are peptides steroids?

Accepted Answer

No. Steroids are lipid-based hormones (like testosterone or cortisol) that enter cells and directly alter gene expression. Peptides are amino acid chains that typically bind to receptors on the outside of the cell membrane to trigger a signaling cascade. They are fundamentally different classes of molecules.

Question 4

What is the difference between a peptide and a protein?

Accepted Answer

The distinction is primarily size. Peptides are short chains (under 50 amino acids), while proteins are longer, complex chains that fold into 3D structures. Because peptides are smaller, they are often easier to synthesize and can be more readily absorbed or utilized by the body.

Question 5

Are peptides legal?

Accepted Answer

The legality of peptides depends on the specific compound and how it is sourced. Some peptides (like Semaglutide or Tirzepatide) are FDA-approved medications available via prescription. Others are available through licensed compounding pharmacies (503A/503B) with a prescription. Many are sold online as 'research chemicals' not approved for human consumption, which exists in a regulatory gray area.

Question 6

What is the FDA Category 1 and Category 2 list?

Accepted Answer

Under the 503A compounding framework, the FDA categorizes bulk drug substances. Category 1 substances are permitted for compounding. Category 2 substances are restricted due to safety or efficacy concerns. In 2026, several peptides (including BPC-157) were reclassified back to Category 1, allowing compounding pharmacies to legally prepare them with a prescription.

Question 7

Do peptides have side effects?

Accepted Answer

Yes. While often well-tolerated, side effects depend on the specific peptide. Common side effects include injection site reactions (redness/itching), temporary water retention (with GH peptides), or nausea (with GLP-1 agonists). Serious side effects can occur, especially with incorrect dosing or contaminated gray-market products.

Question 8

Will peptides show up on a drug test?

Accepted Answer

Standard employment drug panels do not test for peptides. However, the World Anti-Doping Agency (WADA) bans many peptides, including BPC-157, TB-500, and GH secretagogues. Athletes subject to WADA or similar anti-doping testing will fail tests if they use banned peptides.

Question 9

How do I reconstitute a peptide?

Accepted Answer

Most research peptides come as a lyophilized (freeze-dried) powder. You must reconstitute them by adding a specific volume of Bacteriostatic Water (BAC water) to the vial. The volume of water determines the concentration (mg/mL). You should inject the water slowly down the side of the vial and gently swirl—never shake—to dissolve the powder.

Question 10

What is the difference between BAC water and sterile water?

Accepted Answer

Bacteriostatic water (BAC water) contains 0.9% benzyl alcohol, which acts as a preservative to prevent bacterial growth. This allows a reconstituted multi-dose vial to remain safe for up to 28 days. Sterile water has no preservative and should only be used for single-use preparations.

Question 11

How should peptides be stored?

Accepted Answer

Unreconstituted (powder) peptides should be stored in the freezer for long-term storage, or in the refrigerator for shorter periods. Keep them away from light. Once reconstituted with BAC water, the vial must be stored in the refrigerator (36-46°F) and typically used within 28 days.

Question 12

Can I pre-fill syringes for travel?

Accepted Answer

It is generally not recommended to store peptides in plastic syringes for extended periods. The peptide can degrade or adhere to the plastic, and pre-filling introduces a higher risk of contamination. It is safer to travel with the vial (kept cold) and draw doses as needed.

Question 13

How are peptides administered?

Accepted Answer

The vast majority of peptides are administered via subcutaneous (SubQ) injection into the fat layer just beneath the skin, usually in the abdomen. Some peptides are available as nasal sprays, topical creams, or oral capsules, but bioavailability is typically highest with injection.

Question 14

What is a peptide cycle?

Accepted Answer

Cycling refers to taking a peptide for a defined period (e.g., 4 to 12 weeks) followed by an off-period. This prevents receptor desensitization (where the body stops responding to the peptide) and allows natural biological systems to normalize.

Question 15

What is a peptide stack?

Accepted Answer

A stack is the use of two or more peptides simultaneously to achieve a synergistic effect. A common example is the 'Wolverine Stack,' which combines BPC-157 and TB-500 for enhanced tissue repair and recovery.

Question 16

How do I calculate my dose?

Accepted Answer

Dose calculation depends on the vial size (mg), the amount of BAC water added (mL), and your target dose (mcg or mg). For example, a 5mg vial mixed with 2mL of water yields a concentration of 2.5mg/mL. A 250mcg (0.25mg) dose would require drawing 0.1mL (10 units on a U-100 insulin syringe). We highly recommend using the PepOS Dose Calculator to avoid math errors.

The Ultimate Peptide FAQ

General Basics

Safety & Legal

Preparation & Storage

Dosing & Administration

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