Category: Guides

Peptides are delicate molecules. Heat, moisture, light, oxygen and even rough handling can break them down, and a degraded peptide isn’t the compound listed on the label anymore. This guide covers how labs typically store peptides in powder and liquid form, and how to recognize when something has gone wrong.

What breaks peptides down?

Factor	What happens
Heat	Speeds up every chemical breakdown reaction
Moisture	Allows hydrolysis, where water splits peptide bonds
Oxygen	Oxidizes sensitive amino acids like methionine, cysteine and tryptophan
Light	UV light can damage certain amino acids
pH extremes	Promotes breakdown and structural changes
Agitation	Shaking can cause peptides to clump (aggregate) or stick to surfaces
Repeated freeze-thaw	Each cycle stresses the molecule, especially in solution

Storing lyophilized (powder) peptides

Lyophilization removes water by freezing the peptide and then pulling the ice off under vacuum. With little water left, most breakdown reactions slow dramatically.

• Long-term: commonly stored frozen at about -20°C (-4°F). Some labs use -80°C for very long storage.
• Short-term: refrigerated at 2–8°C (36–46°F) is common for weeks to months, depending on the compound.
• Room temperature: many lyophilized peptides tolerate shipping at room temperature for a few days, but it isn’t ideal for storage.
• Keep it sealed and dark. Store vials in their box or an opaque container.
• Warm before opening. Let a cold vial reach room temperature before opening it, or moisture from the air will condense inside.
• Use a desiccant in the storage container if humidity is a concern.

Storing reconstituted (liquid) peptides

Once a peptide is dissolved, water is back in the picture and breakdown speeds up.

• Refrigerate at 2–8°C. Use the main body of the fridge, not the door, where temperatures swing.
• Protect from light.
• Avoid freezing and thawing a multi-use vial repeatedly. Labs that need long storage split a solution into single-use portions (aliquots) before freezing.
• Label everything with the compound, concentration and mixing date.
• Check compound-specific data. Stability in solution can range from days to weeks depending on the peptide.

Bacteriostatic water vs sterile water

	Bacteriostatic water	Sterile water
Contents	Sterile water + 0.9% benzyl alcohol	Sterile water only
Purpose	Preservative slows bacterial growth after the vial is punctured	No preservative
Intended use	Multiple-use vials	Single use; discard after opening

Some peptides dissolve better in specific solutions, such as dilute acetic acid, depending on their chemistry. Follow compound-specific guidance.

Reconstitution handling tips

1. Clean vial tops with an alcohol swab and let them dry.
2. Add liquid slowly, aiming it down the inside wall of the vial rather than directly onto the powder.
3. Swirl gently or roll the vial between your palms. Don’t shake.
4. Give it a few minutes to dissolve fully.
5. Record the volume added so you know the concentration. Our Peptide Math page explains the calculation.

Signs a peptide may have degraded

• Cloudiness, haze or particles in a solution that should be clear
• Color changes
• Powder that looks wet, sticky, shrunken or collapsed
• A cracked seal or loose cap

When in doubt, discard it. Degradation can’t always be seen, which is why storage matters from day one.

Shipping and receiving

Put peptides into proper storage as soon as they arrive. If a package sat in a hot mailbox or truck for days, stability may be affected. Reputable suppliers ship with cold packs when needed and list storage conditions on the label. See our Reading Labels page.

If you compete in a tested sport, peptides are a minefield. Many popular compounds are banned, rules are strict, and “it’s undetectable” claims have ended careers. This guide explains how the World Anti-Doping Agency (WADA) classifies peptides, how testing differs from workplace drug screens, and what athletes should do.

How the WADA Prohibited List works

WADA publishes an updated Prohibited List every year, effective January 1. National agencies like USADA enforce it, and many leagues and federations adopt it. Substances are grouped into categories. The two that matter most for peptides are:

S0: Non-approved substances

Any substance not approved by a government health authority for human therapeutic use is banned at all times, even if it isn’t named elsewhere on the list. WADA specifically names BPC-157 as an example.

S2: Peptide hormones, growth factors, related substances and mimetics

This category covers a long list, including:

• Growth hormone and its fragments
• GHRH and its analogs, such as CJC-1295, sermorelin and tesamorelin
• GH secretagogues and ghrelin mimetics, such as ipamorelin, GHRP-2, GHRP-6 and MK-677 (ibutamoren)
• Growth factors and growth factor modulators, including thymosin beta-4 and its derivatives such as TB-500
• Substances that increase red blood cell production, like EPO
• Hormones that affect testosterone production, like hCG and LH (banned in males)

Always check the current year’s list; compounds get added and clarified regularly.

Quick reference

Compound	WADA category	Status
BPC-157	S0	Prohibited at all times
TB-500 / thymosin beta-4	S2	Prohibited at all times
CJC-1295, sermorelin, tesamorelin	S2	Prohibited at all times
Ipamorelin, GHRP-2, GHRP-6	S2	Prohibited at all times
MK-677 (ibutamoren)	S2	Prohibited at all times
Semaglutide, tirzepatide	Not listed at time of writing	Check the current list; WADA monitors emerging substances
GHK-Cu (topical cosmetic)	Not specifically listed at time of writing	Check with your anti-doping agency

This table is a general guide, not a ruling. Use your anti-doping agency’s substance lookup tool (such as Global DRO) for any specific product.

How anti-doping tests detect peptides

A standard workplace drug test screens for a short list of drugs like THC, opioids, cocaine and amphetamines. It won’t find peptides. Anti-doping labs are a completely different operation:

• Mass spectrometry (often LC-MS/MS) can identify specific peptides and their breakdown products in urine or blood.
• Targeted methods are developed for specific compounds as they become popular.
• Biomarker approaches look for changes in the body, such as GH-related markers, rather than the substance itself.
• Stored samples can be retested for years later as methods improve.

Short half-lives can make detection windows narrow, but that doesn’t make a compound safe to use. Retesting of stored samples has led to sanctions long after competition.

Strict liability: why intent doesn’t matter

Under the World Anti-Doping Code, athletes are responsible for any prohibited substance found in their sample, whether or not they meant to take it. Contaminated supplements and mislabeled products have caused positive tests. With research-market peptides, where labeling and purity vary, that risk is higher.

Therapeutic Use Exemptions (TUE)

If an athlete has a legitimate medical need for a prohibited substance, they can apply for a TUE through their anti-doping organization. TUEs require medical documentation and are generally only granted for approved medications with a clear diagnosis. Research-only compounds are very unlikely to qualify.

Beyond WADA

• NCAA has its own banned-drug classes that include peptide hormones and analogs.
• Professional leagues (NFL, MLB, NBA, NHL, UFC and others) have their own policies, often based on WADA’s.
• Military and some employers have separate rules for supplements and unapproved substances.

Bottom line for athletes

1. Assume any injectable peptide not prescribed for a documented condition is banned.
2. Check every product and supplement with your anti-doping agency’s tools.
3. Don’t rely on “undetectable” claims.
4. Talk to your team physician before using anything new.

Related: BPC-157 vs TB-500 · GH secretagogues · Safety & Sources