What Are Peptides? Complete Beginner's Guide to Peptide Research [2026]

Peptides are short chains of amino acids that act as signaling molecules in your body. This comprehensive guide explains everything beginners need to know about peptides—from basic science to practical information about dosing, injections, and terminology.

If you've seen terms like "GLP-1 agonist," "BPC-157," or "GHRP-6" and felt completely lost, you're not alone. This guide will take you from zero knowledge to confidently understanding peptides. No prior science background required.

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Table of Contents

1. What Are Peptides?
2. Understanding Peptide Names
3. How Peptides Work in Your Body
4. Types of Peptides by Category
5. Peptide Dosing Basics
6. How to Inject Peptides
7. When to Take Peptides
8. How to Store Peptides
9. Peptide Terminology Glossary
10. Are Peptides Legal?
11. Peptide Safety
12. FAQs

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What Are Peptides?

The Basic Definition

Peptides are short chains of amino acids linked together by peptide bonds. Think of amino acids as individual LEGO blocks, and peptides as small structures built from those blocks.

Your body has 20 different amino acids that can be combined in countless ways. When you string together:

• 2-50 amino acids → Peptide
• 50-100 amino acids → Polypeptide
• 100+ amino acids → Protein

So peptides are essentially "mini-proteins" - small enough to be absorbed and used quickly, but large enough to carry specific instructions to your cells.

Why Peptides Matter

Your body naturally produces thousands of peptides that act as messengers. They tell your cells what to do:

• Insulin (a peptide) tells cells to absorb glucose
• Oxytocin (a peptide) signals bonding and trust
• Ghrelin (a peptide) signals hunger
• Growth hormone releasing hormone tells your pituitary to release growth hormone

When scientists create synthetic peptides, they're essentially creating messengers that can communicate specific instructions to your body.

Natural vs. Synthetic Peptides

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Understanding Peptide Names and Numbers

This is where most beginners get confused. Let's decode the peptide naming system so you can understand what BPC-157, GLP-1, GHRP-6, and other peptide names actually mean.

Why the Confusing Names?

Peptide names typically come from:

1. Abbreviations of their function (GLP-1 = Glucagon-Like Peptide 1)
2. Research codes (BPC-157 = Body Protection Compound, sequence 157)
3. Company codes (PT-141 = Palatin Technologies compound 141)
4. Amino acid sequences (GHK-Cu = Glycine-Histidine-Lysine + Copper)

Common Naming Patterns Explained

GLP-1, GIP, GLP-1/GIP:

• GLP-1 = Glucagon-Like Peptide 1 (a gut hormone)
• GIP = Glucose-dependent Insulinotropic Polypeptide
• When you see "GLP-1 agonist" it means something that ACTIVATES GLP-1 receptors

Numbers in names:

• BPC-157 = The 157th compound in that research series
• GHRP-6 = Growth Hormone Releasing Peptide, version 6
• TB-500 = Thymosin Beta-4 fragment, compound 500

Letters at the end:

• CJC-1295 DAC = "Drug Affinity Complex" - modified to last longer
• N-Acetyl Semax = Acetyl group added for stability

Real Example: Decoding "Tirzepatide"

Tirzepatide is sold as Mounjaro/Zepbound. It's a "dual GIP/GLP-1 receptor agonist."

Breaking that down:

• Dual = Affects two receptors
• GIP = One type of gut hormone receptor
• GLP-1 = Another type of gut hormone receptor
• Receptor = A protein on cells that receives signals
• Agonist = Something that ACTIVATES a receptor

So tirzepatide activates both GIP and GLP-1 receptors, giving stronger effects than single-target drugs.

Quick Reference: Common Peptide Abbreviations

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How Do Peptides Work?

The Lock and Key System

Imagine your cells have thousands of tiny "locks" on their surface called receptors. Peptides are specific "keys" that fit into these locks.

When a peptide (key) binds to a receptor (lock):

1. The receptor changes shape
2. This triggers a cascade inside the cell
3. The cell performs a specific action

Different peptides fit different receptors, which is why they have different effects.

Types of Peptide Actions

Agonists - ACTIVATE a receptor (turn it ON)

• Example: Semaglutide is a GLP-1 receptor agonist - it turns ON GLP-1 receptors

Antagonists - BLOCK a receptor (turn it OFF)

• Example: Some peptides block myostatin receptors to allow more muscle growth

Modulators - ADJUST receptor activity (fine-tune)

• Example: Selank modulates GABA receptors, increasing their sensitivity

The Receptor Families

G-Protein Coupled Receptors (GPCRs): Most peptides work through these. When activated, they trigger internal cell signaling cascades.

Enzyme-Linked Receptors: Some peptides activate these, which directly trigger enzyme activity inside cells.

Ion Channel Receptors: Less common for peptides, but some affect these to change electrical signals in cells.

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Types of Peptides by Category

Explore all peptides in our complete peptide database or browse by category below.

By Primary Function

Weight Loss / Metabolic Peptides:

• GLP-1 agonists (semaglutide, tirzepatide, liraglutide)
• Dual/triple agonists (retatrutide)
• AOD-9604

Growth Hormone Peptides:

• GHRH analogs (sermorelin, CJC-1295, tesamorelin)
• GHRPs (ipamorelin, GHRP-2, GHRP-6, hexarelin)

Healing & Recovery Peptides:

• BPC-157 (tissue repair)
• TB-500 (systemic healing)
• GHK-Cu (skin/wound healing)

Cognitive / Nootropic Peptides:

• Semax (focus, neuroprotection)
• Selank (anxiety, cognition)
• Dihexa (memory)

Anti-Aging Peptides:

• Epithalon (telomeres)
• GHK-Cu (skin aging)
• NAD+ precursors

Sexual Health Peptides:

• PT-141 / Bremelanotide (libido)
• Kisspeptin (hormonal regulation)

Immune Support Peptides:

• Thymosin Alpha-1 (immune modulation)
• LL-37 (antimicrobial)

Cosmetic / Skin Peptides:

• Argireline (wrinkle reduction)
• Matrixyl (collagen stimulation)
• Melanotan II (tanning)

By Research Status

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Peptide Dosing: How to Measure and Calculate

Understanding Units

Micrograms (mcg or μg):

• 1 milligram (mg) = 1,000 micrograms (mcg)
• Most peptides are dosed in mcg
• Example: "250 mcg BPC-157 twice daily"

Milligrams (mg):

• Used for larger doses
• Example: "2.4 mg semaglutide weekly"

International Units (IU):

• Measures biological activity, not weight
• Used for: HGH, insulin, HCG
• Example: "2 IU HGH daily"

How Peptides Are Sold

Lyophilized (Freeze-Dried) Powder:

• Most common form for research peptides
• White/off-white powder in a sealed vial
• Must be reconstituted (mixed with water) before use
• More stable than liquid form

Pre-Mixed Liquid:

• Already reconstituted
• Convenient but shorter shelf life
• Used in prescription pens (like Ozempic)

Typical Vial Sizes:

• 5mg vials (common for BPC-157, TB-500)
• 2mg, 10mg vials (various peptides)
• Prescription pens contain varying amounts

Reconstitution: Mixing Peptides

What You Need:

• Bacteriostatic water (BAC water) - water with 0.9% benzyl alcohol preservative
• Insulin syringes
• Alcohol swabs

Basic Process:

1. Clean vial top with alcohol swab
2. Draw up bacteriostatic water into syringe
3. Inject water SLOWLY into vial, aiming at the glass wall (not directly at powder)
4. Let it sit or gently swirl - NEVER shake
5. Once dissolved, it's ready to use
6. Refrigerate after reconstitution

Calculating Your Dose:

If you have a 5mg vial and add 2mL of water:

• 5mg = 5,000mcg
• 5,000mcg ÷ 2mL = 2,500mcg per mL
• 1mL = 100 units on an insulin syringe
• So each 10 units = 250mcg

Common Reconstitution Math:

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How to Inject Peptides: Administration Methods

Subcutaneous Injection (SubQ)

What it is: Injecting into the fat layer just under the skin

Most common for: Most peptides (BPC-157, TB-500, GH peptides, semaglutide)

Sites:

• Belly fat (most common) - 2 inches from belly button
• Outer thigh
• Back of upper arm
• Love handles

Technique:

1. Clean injection site with alcohol swab
2. Pinch skin to lift fat away from muscle
3. Insert needle at 45-90° angle (depending on fat thickness)
4. Inject slowly
5. Remove needle, apply light pressure if needed

Needle size: 29-31 gauge, 1/2 inch (insulin syringes)

Intramuscular Injection (IM)

What it is: Injecting directly into muscle tissue

Used for: Some peptides when faster absorption is needed

Sites:

• Deltoid (shoulder)
• Vastus lateralis (outer thigh)
• Glutes (upper outer quadrant)

Needle size: 25-27 gauge, 1-1.5 inches

Intranasal

What it is: Spraying into the nose

Used for: Semax, Selank, some other cognitive peptides

Advantage: Bypasses digestion, faster brain access

Oral

What it is: Swallowing as a pill or capsule

Used for: Some peptides with special formulations

Examples: Oral semaglutide (Rybelsus), some bioregulators

Note: Most peptides are destroyed by stomach acid, so oral forms require special protection

Topical

What it is: Applied to the skin

Used for: GHK-Cu, cosmetic peptides

Advantage: Targeted local effects

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When to Take Peptides: Timing and Frequency

General Principles

Fasted vs. Fed:

• Most peptides absorb better on an empty stomach
• GH secretagogues especially need fasted state (insulin blocks GH release)
• GLP-1 agonists can be taken regardless of food

Time of Day:

• Morning: Cognitive peptides (Semax, Selank)
• Before bed: GH secretagogues (Ipamorelin, GHRP-6)
• Around injury: Healing peptides (BPC-157 can be near injury site)
• Weekly same day: Long-acting (semaglutide, tirzepatide)

Common Protocols

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How to Store Peptides

Lyophilized (Powder) Form

Refrigerator (2-8°C / 36-46°F):

• Good for months to years
• Stable at this temperature

Freezer (-20°C / -4°F):

• Best for long-term storage
• Can extend shelf life significantly

Room temperature:

• Avoid if possible
• Short exposure (hours) usually okay

After Reconstitution

ALWAYS refrigerate - no exceptions

Never freeze reconstituted peptides - can damage structure

Use within:

• 2-4 weeks is common guideline
• Bacteriostatic water helps preserve longer than sterile water

Signs of Degradation

Discard if you see:

• Cloudiness (should be clear)
• Particles floating
• Color change (should be clear/slightly yellow)
• Unusual smell

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Peptide Terminology Glossary

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Are Peptides Legal? Research Status and Regulation

FDA Approval Process

1. Preclinical - Lab and animal studies
2. IND Application - Request to begin human trials
3. Phase 1 - Safety testing (20-100 people)
4. Phase 2 - Efficacy and dosing (100-500 people)
5. Phase 3 - Large scale effectiveness (1,000-5,000 people)
6. FDA Review - Application reviewed
7. Approval - Can be prescribed legally

What "Research Chemical" Means

• NOT FDA-approved for human use
• Sold "for research purposes only"
• Legal to purchase in most places
• No guaranteed purity or safety
• Use at your own risk

Currently FDA-Approved Peptides (Examples)

• Semaglutide (Ozempic, Wegovy, Rybelsus)
• Tirzepatide (Mounjaro, Zepbound)
• Liraglutide (Victoza, Saxenda)
• Tesamorelin (Egrifta)
• Bremelanotide/PT-141 (Vyleesi)
• Insulin (various)
• Oxytocin (Pitocin)

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Peptide Safety: What You Need to Know

General Principles

1. Start low, go slow - Begin with lowest effective dose
2. One change at a time - Don't start multiple new things together
3. Know what's normal - Research expected effects and side effects
4. Quality matters - Poor quality products have unknown risks
5. Not a replacement for medicine - Peptides don't cure diseases

Red Flags to Watch For

In Products:

• No third-party testing
• Prices too good to be true
• Vague sourcing
• No batch numbers

In Your Body:

• Unusual injection site reactions
• Unexpected symptoms
• Allergic reactions
• Signs of infection

When to Seek Medical Help

• Severe allergic reaction
• Signs of infection (redness spreading, fever, pus)
• Unexpected severe side effects
• If you have underlying health conditions

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Frequently Asked Questions About Peptides

Q: Are peptides legal? A: FDA-approved peptides are legal with prescription. Research peptides are legal to purchase but not approved for human use. Laws vary by country.

Q: Are peptides steroids? A: No. Peptides are chains of amino acids. Steroids are a completely different chemical class based on a four-ring structure.

Q: Do peptides require PCT (post-cycle therapy)? A: Unlike steroids, most peptides don't suppress natural hormone production in ways that require PCT. Exception: Some may temporarily affect the GH axis.

Q: Can peptides be detected in drug tests? A: Some can. Many peptides are banned by WADA for competitive athletes. GH secretagogues, SARMs, and some others are tested for.

Q: How long until I see results? A: Varies hugely by peptide:

• GLP-1 agonists: Often weeks to months for significant weight loss
• Healing peptides: Some report improvements in 1-2 weeks
• GH secretagogues: Gradual effects over weeks to months
• Cognitive: Some notice effects same day, others take weeks

Q: Can I combine peptides? A: Some combinations are well-established (like Ipamorelin + CJC-1295). Others may have unknown interactions. Research each combination carefully.

Q: Why are some peptides so expensive? A: FDA-approved peptides (like semaglutide) require expensive development, trials, and manufacturing. Research peptides are cheaper but unregulated.

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What to Do Next

You now have a solid foundation for understanding peptides. Here's what to do next:

1. Identify your goals - What are you trying to achieve? Weight loss, healing, cognitive enhancement, anti-aging?
2. Research specific peptides - Browse our complete peptide database with 98+ peptides, or try our peptide quiz to find peptides matched to your goals
3. Compare peptides - Use our peptide comparison tool to evaluate different options side-by-side
4. Build a stack - Our stack builder helps you create peptide combinations for your goals
5. Understand the evidence - Check the research status and clinical trials behind your peptide of interest
6. Consider the legal/safety aspects - Know the difference between FDA-approved and research peptides
7. If using prescription peptides - Work with a healthcare provider

Remember: This guide is for educational purposes. Peptides (especially research compounds) carry risks. Make informed decisions and consider consulting healthcare professionals.

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This comprehensive guide is for educational purposes only. It does not constitute medical advice. Always consult qualified healthcare providers for personal medical decisions. Research peptides are not approved for human use.