How long do lyophilized peptides last?

Lyophilized (freeze-dried) peptides are highly stable. When stored properly in a freezer at -20°C (-4°F), most lyophilized peptides remain viable for 2-3 years or longer. Refrigerated at 2-8°C, they typically last 6-12 months. At room temperature, shelf life drops significantly — weeks to a few months depending on the peptide. Always store lyophilized peptides cold for maximum longevity.

Do I need to freeze reconstituted peptides?

No — never freeze reconstituted peptides. Freezing a liquid peptide solution creates ice crystals that physically damage peptide chains through shear forces, causing aggregation and loss of potency. Reconstituted peptides should be refrigerated at 2-8°C (36-46°F) and used within 28-30 days when prepared with bacteriostatic water, or within 24 hours when prepared with sterile water.

Can I store multiple peptides in the same fridge?

Yes, storing multiple peptide vials in the same refrigerator is perfectly fine. Each vial is sealed and independent. For organization, keep them upright in a small box or container, and label each vial clearly with the peptide name, concentration, and reconstitution date. Avoid placing vials in the door where temperature fluctuates with opening and closing.

How do I know if my peptide has gone bad?

For reconstituted peptides, look for cloudiness or haziness (should be perfectly clear), visible particles or floaters, discoloration (should be colorless), or unusual smell. For lyophilized peptides, signs of degradation include discoloration of the powder (yellow or brown tinting), the powder becoming gummy or sticky, or the cake collapsing into a wet appearance. When in doubt, discard and use a fresh vial.

Should I use bacteriostatic water or sterile water for reconstitution?

Bacteriostatic water is strongly preferred for multi-dose vials. It contains 0.9% benzyl alcohol as a preservative, which inhibits bacterial growth across repeated needle entries for approximately 28 days. Sterile water has no preservative and must be used within 24 hours of reconstitution. The only reason to use sterile water is for single-use applications or if a specific peptide is incompatible with benzyl alcohol.

Can peptides survive shipping without cold packs?

Lyophilized peptides can tolerate brief room temperature exposure during shipping (a few days) without significant degradation — the freeze-dried form is much more stable than solution. However, extended heat exposure (above 30°C / 86°F for multiple days) can accelerate degradation. Reputable suppliers use insulated packaging and cold packs for warm-weather shipping. Reconstituted peptides should never be shipped without continuous cold chain.

How long can reconstituted BPC-157 last in the fridge?

BPC-157 reconstituted with bacteriostatic water and stored at 2-8°C typically remains viable for 28-30 days. Some users report using it up to 6 weeks, but potency gradually decreases over time. BPC-157 is considered relatively stable compared to some other peptides, but the 28-day guideline provides the best balance of convenience and reliability. Always discard if the solution appears cloudy or discolored.

Does light exposure damage peptides?

Yes, many peptides are photosensitive — UV light and even ambient room light can accelerate degradation over time. This is particularly relevant for reconstituted peptides in clear glass vials. Store vials in the original box, wrap in aluminum foil, or keep in an opaque container in the refrigerator. Brief light exposure during dosing is not a concern, but avoid leaving vials on a counter in direct sunlight.

Peptide Storage & Shelf Life Guide

Everything you need to know about storing peptides properly — lyophilized vs reconstituted shelf life, temperature requirements, light sensitivity, and how to maximize potency over time.

Compiled by PeptideWiki Editorial Team

Lyophilized vs. Reconstituted: What's the Difference?

The form your peptide is in — lyophilized powder or reconstituted liquid — dramatically affects how long it lasts and how it should be stored. Understanding this distinction is the foundation of proper peptide storage.

Lyophilized (Freeze-Dried) Peptides

Lyophilization removes virtually all water from the peptide, leaving a dry powder or "cake" in the vial. Without water, the chemical reactions that cause degradation (hydrolysis, oxidation, deamidation) occur extremely slowly. This is why lyophilized peptides can last months to years when stored properly — the absence of water is their primary defense against breakdown.

Reconstituted Peptides

Once you add bacteriostatic water (or any diluent) to a lyophilized peptide, the clock starts ticking. Water reactivates degradation pathways, and the liquid form is far more susceptible to temperature changes, light exposure, and bacterial contamination. A reconstituted peptide's shelf life drops from months/years to approximately 28-30 days with bacteriostatic water, or just 24 hours with sterile water.

Property	Lyophilized	Reconstituted (BAC Water)	Reconstituted (Sterile Water)
Shelf Life (Frozen)	2-3+ years	Do not freeze	Do not freeze
Shelf Life (Refrigerated)	6-12 months	28-30 days	24 hours
Shelf Life (Room Temp)	Weeks to months	Hours to days	Hours
Light Sensitivity	Moderate	High	High
Contamination Risk	Very low (sealed)	Moderate (each needle entry)	High (no preservative)

Key takeaway: Only reconstitute what you'll use within 28-30 days. If you have multiple vials, keep them lyophilized in the freezer until you need them. Reconstitute one vial at a time.

Temperature Guide: Refrigeration, Freezing & Room Temp

Temperature is the single most important factor in peptide storage. Every degree above optimal storage temperature accelerates degradation. Here's what each temperature range means for your peptides.

Freezer Storage: -20°C (-4°F)

Best for long-term storage of lyophilized peptides. At -20°C, chemical reactions essentially halt, preserving the peptide's molecular integrity for years. A standard kitchen freezer works fine — no need for an ultra-cold freezer. Keep peptides in their original sealed vials, ideally inside a sealed container or bag to protect against moisture and frost.

Refrigerator: 2-8°C (36-46°F)

The standard storage temperature for reconstituted peptides and short-to-medium term storage of lyophilized peptides. Place vials on a main shelf (not the door) where temperature stays most consistent. Keep vials upright to prevent the solution from contacting the rubber stopper for extended periods.

Room Temperature: 20-25°C (68-77°F)

Acceptable only for brief handling during reconstitution and dosing. Lyophilized peptides can tolerate room temperature for short periods (shipping, handling), but should not be stored at room temperature long-term. Reconstituted peptides should never sit at room temperature for more than 30-60 minutes during use.

Heat Exposure: Above 30°C (86°F)

Avoid at all costs. Heat exposure accelerates every degradation pathway — hydrolysis, oxidation, aggregation. Even a few hours at elevated temperatures can measurably reduce potency. Never leave peptides in a car, near a window, or near heat-generating appliances.

Quick Reference: Temperature Ranges

Temperature	Use Case	Duration
-20°C (-4°F)	Long-term lyophilized storage	Years
2-8°C (36-46°F)	Reconstituted peptides & short-term lyophilized	28-30 days (reconstituted) / months (lyophilized)
20-25°C (68-77°F)	Brief handling only	Minutes during dosing
>30°C (86°F)	Avoid entirely	Accelerates degradation

How to Store Peptides Properly

Proper storage goes beyond just refrigeration. These best practices protect against all the major degradation factors — temperature, light, moisture, and contamination.

Storage Best Practices Checklist:

Keep vials upright — prevents solution from prolonged contact with the rubber stopper, which can leach compounds
Store on a main refrigerator shelf — avoid the door (temperature fluctuates) and areas near the freezer vent (risk of freezing)
Protect from light — keep vials in their original box, wrap in aluminum foil, or use an opaque container
Maintain consistent temperature — avoid repeatedly taking vials in and out — remove, draw dose, return promptly
Use a dedicated container or box — keeps vials organized, protected from light, and separated from food items
Label every reconstituted vial — include peptide name, concentration, date reconstituted, and 28-day expiration date
Swab vial tops before every draw — alcohol swab reduces bacterial introduction with each needle puncture

Desiccants for Lyophilized Storage

If storing lyophilized peptides for extended periods, consider placing a small desiccant packet inside the storage container (not inside the vial). Desiccants absorb ambient moisture that could seep past the vial stopper over months of storage. This is especially important if your refrigerator or freezer accumulates frost.

Vacuum-Sealed Storage

For maximum long-term preservation, some users vacuum-seal lyophilized vials in moisture-barrier bags before freezing. This eliminates moisture exposure entirely and can extend shelf life well beyond 3 years. This is optional but worthwhile if you're storing a larger supply.

Storing Reconstituted Peptides

Once a peptide is reconstituted, storage requirements become more critical. The liquid form is inherently less stable, and every needle entry introduces potential contamination.

With Bacteriostatic Water (~28-30 Days)

Bacteriostatic water contains 0.9% benzyl alcohol, which continuously inhibits bacterial growth. This allows multi-dose use over approximately 28-30 days when refrigerated. The preservative doesn't prevent degradation of the peptide itself — it only controls bacterial contamination. Peptide potency still gradually decreases over time due to hydrolysis and oxidation.

With Sterile Water (~24 Hours)

Sterile water contains no preservative. Each needle puncture introduces bacteria into an unprotected solution. For this reason, reconstituted peptides using sterile water should be used within 24 hours or discarded. Only use sterile water when you intend to use the entire vial in a single session.

The 28-Day Rule: What Happens After?

After 28-30 days, the bacteriostatic preservative's effectiveness diminishes, especially with many needle entries. The peptide itself also continues to degrade. While the solution may still look clear, potency is likely reduced and contamination risk is elevated. The 28-day guideline exists because it represents the point where both bacterial protection and peptide integrity begin to fall below reliable levels.

Never freeze reconstituted peptides. The freeze-thaw cycle creates ice crystals that physically shear peptide chains, causing aggregation and loss of bioactivity. Once reconstituted, the peptide stays refrigerated (2-8°C) until used or discarded.

For a detailed walkthrough of the reconstitution process itself, see our How to Reconstitute Peptides guide.

Peptide-Specific Storage Notes

While general storage guidelines apply to all peptides, some have specific considerations worth noting. These differences relate to molecular stability, sensitivity to light or temperature, and degradation characteristics.

Peptide	Lyophilized Stability	Reconstituted Stability	Special Notes
BPC-157	High — very stable	28-30 days (some report 6 weeks)	Among the most stable peptides; tolerates brief warmth
TB-500	High	28-30 days	Very stable in both forms; light sensitivity is low
CJC-1295	Moderate-High	21-28 days	DAC variant is more stable; non-DAC degrades faster in solution
Ipamorelin	High	28-30 days	Relatively robust; standard storage applies
Semaglutide	Very High	28-30 days (potentially longer)	Engineered for stability; albumin binding extends half-life
GHK-Cu	Moderate	14-21 days	Copper complex is light-sensitive; wrap in foil; shorter reconstituted life
Melanotan II	High	28-30 days	Photosensitive — protect from light in both forms
PT-141	High	28-30 days	Similar stability to Melanotan II; protect from light
Epitalon	High	14-21 days	Short reconstituted life; reconstitute only when starting a cycle
DSIP	Moderate	14-21 days	Less stable than many peptides; use promptly after reconstitution

General rule: When in doubt about a specific peptide's stability, err on the side of caution — store cold, protect from light, and use within 3-4 weeks of reconstitution. Check each peptide's full profile for detailed information.

Signs Your Peptides Have Degraded

Knowing what to look for helps you avoid using compromised peptides. Some degradation signs are obvious; others are subtle. Here's what to check.

Reconstituted Peptides

Cloudiness or haziness — a properly reconstituted peptide should be perfectly clear and colorless
Visible particles or floaters — indicates aggregation (peptide molecules clumping together) or contamination
Discoloration — any yellow, brown, or pink tinting suggests chemical degradation or oxidation
Unusual smell — may indicate bacterial growth, especially if using sterile water past 24 hours
Reduced effectiveness — if the peptide seems less effective at the same dose, degradation may be the cause

Lyophilized Peptides

Discoloration of the powder — lyophilized powder should be white to off-white; yellow or brown indicates degradation
Collapsed or wet-looking cake — the powder should appear dry and intact; a collapsed or gummy appearance suggests moisture exposure
Difficulty dissolving — if the peptide takes unusually long to dissolve or produces a cloudy solution, it may be degraded

When in doubt, discard and use a fresh vial. Peptides are relatively inexpensive compared to the risks of using a degraded or contaminated solution. If anything looks, smells, or seems off — start over with a new vial.

Traveling with Peptides

Traveling with peptides requires planning to maintain the cold chain. The biggest risks are temperature exposure during transit and prolonged time without refrigeration.

Lyophilized Peptides (Easier)

Unreconstituted peptides are the most travel-friendly. They can tolerate room temperature for several days without significant degradation. For short trips (1-3 days), lyophilized vials can travel without cold packs. For longer trips or hot climates, use an insulated pouch with an ice pack as a precaution. Reconstitute at your destination when you're ready to use.

Reconstituted Peptides (More Care Needed)

Reconstituted peptides must stay refrigerated (2-8°C) at all times. Use a small insulated cooler bag with gel ice packs — the kind used for transporting insulin works well. Avoid direct contact between ice packs and vials (can freeze the solution). Plan your trip so you can get the vials back into a refrigerator within 4-6 hours.

Air Travel Tips

Carry on, don't check: Checked luggage can be exposed to extreme temperatures in the cargo hold
Keep vials in a clear bag: TSA security may want to inspect medical supplies
Bring syringes in original packaging: Unopened, sealed syringes are easier to explain at security
Consider a doctor's note: For prescribed peptides, a letter from your prescriber can smooth the security process
Gel ice packs must be frozen solid: TSA allows frozen gel packs for medical items but may confiscate partially melted ones

Pro tip: If your trip is longer than 3-4 days, consider bringing lyophilized vials and a small vial of bacteriostatic water instead. Reconstitute at your destination, eliminating the cold chain challenge entirely.

Common Storage Mistakes to Avoid

These mistakes are responsible for the majority of peptide potency loss. Each one is preventable with proper awareness.

Freezing reconstituted peptides

Ice crystals damage peptide chains through shear forces, causing irreversible aggregation and potency loss

Storing vials in the refrigerator door

Door compartments experience the most temperature fluctuation from repeated opening — the main shelf is more stable

Leaving reconstituted vials at room temperature

Accelerates degradation and bacterial growth — potency can drop significantly within days

Not labeling reconstituted vials

Risk of mixing up peptides, concentrations, or using expired solutions — always label with name, concentration, and date

Exposing vials to direct sunlight or UV light

Many peptides are photosensitive — light accelerates chemical degradation and reduces potency

Repeated freeze-thaw cycles for lyophilized peptides

Each cycle introduces moisture that degrades the powder — keep frozen vials frozen until ready to reconstitute

Storing near heat sources (on top of fridge, near stove)

Heat is the primary enemy of peptide stability — even a few degrees above optimal can shorten shelf life

Using peptides past the 28-day reconstitution window

Even with bacteriostatic water, preservative effectiveness diminishes and bacterial load can accumulate

Frequently Asked Questions

Next Steps

Now that you know how to store peptides properly, explore these resources to continue your research.

Reconstitution Guide

Step-by-step instructions for reconstituting lyophilized peptides with bacteriostatic water.

Read Guide

Dosage Calculator

Calculate exact reconstitution volumes and injection doses for any peptide.

Open Calculator

Quality & COA Guide

Learn how to evaluate peptide quality, read COAs, and identify reputable suppliers.

Read Guide