How to Store Peptides

Best practices for storing lyophilised and reconstituted peptides, including temperature requirements, light exposure, shelf life, and travel tips.

Proper storage is critical to preserving peptide potency. Improper storage is one of the most common reasons peptides degrade prematurely. This guide covers best practices for both lyophilised and reconstituted peptides.

Lyophilised (dry) storage

Lyophilised peptides are significantly more stable than their reconstituted counterparts. When stored correctly, many lyophilised peptides retain full potency for 12–24 months.

Short-term (up to 6 months): Store in a refrigerator at 2–8°C. Keep the vial sealed and in the dark.
Long-term (6+ months): Store in a freezer at -20°C or below. Allow the vial to return to room temperature before opening to prevent moisture condensation inside the vial.
Keep sealed: Do not open lyophilised vials until you are ready to reconstitute. Once opened, even dry peptide is exposed to atmospheric moisture.

Reconstituted storage

Once reconstituted, peptides are far more susceptible to degradation. Bacteriostatic water (BW) extends usable life, but refrigeration is still essential.

Always refrigerate reconstituted peptides immediately at 2–8°C.
Typical usable window: 4–6 weeks for most peptides when stored in BW at refrigerator temperatures.
Do not leave at room temperature for extended periods. Degrade rates accelerate rapidly above 8°C.
Keep away from light: Store in the original packaging or a dark drawer. UV exposure accelerates degradation.

Shelf life by peptide type

Different peptide families have different stability profiles. The following are general guidelines — specific products may vary:

Peptide category	Lyophilised shelf life	Reconstituted shelf life
Growth hormone secretagogues (e.g. Ipamorelin)	18–24 months (frozen)	4–6 weeks (refrigerated)
Tissue repair (e.g. BPC-157, TB-500)	24+ months (frozen)	4–6 weeks (refrigerated)
GLP-1 agonists (e.g. Semaglutide)	12–18 months (frozen)	4 weeks (refrigerated)
Melanocortins (e.g. PT-141, Melanotan II)	12–18 months (frozen)	3–4 weeks (refrigerated)

Light and temperature

Two environmental factors are particularly damaging to peptides:

Heat: Peptide bonds are susceptible to hydrolysis at elevated temperatures. Even brief exposure to temperatures above 25°C can reduce potency, particularly in reconstituted form.
UV and visible light: Photodegradation is a concern especially for peptides containing tyrosine, tryptophan, or phenylalanine residues (common in growth hormone secretagogues). Store all peptides in dark conditions.

Freezing reconstituted peptides

Freezing reconstituted peptides is sometimes necessary for extended storage, but carries risks:

Ice crystal formation can physically damage peptide structure.
Repeated freeze-thaw cycles are cumulative in their damaging effect.
If you must freeze, divide into single-dose aliquots using small vials to minimise the number of freeze-thaw cycles each aliquot undergoes.

As a general rule: only freeze reconstituted peptides if the storage period must exceed 6 weeks. Otherwise, refrigeration in BW is preferable.

Travel tips

Travelling with peptides presents challenges around temperature control and legality. Practical tips:

Use a small insulated travel case with ice packs to maintain 2–8°C during transit.
Most airline regulations permit medical cooling devices in carry-on luggage — check with your airline before travel.
Review the legal status of the peptide in your destination country before travelling. Regulations vary significantly across jurisdictions.
Keep the original vial with manufacturer labelling intact where possible.