Safety first: what to know before any peptide protocol

Sourcing is the #1 safety variable

Research-grade peptides vary wildly in purity. Contamination — bacterial endotoxin, residual solvents, incorrect peptide entirely — is the single biggest practical risk. Use sources with third-party HPLC and mass-spec testing. Lot numbers and certificates of analysis should be available on request. The Sourcing & CoA guide goes deep on this; treat it as required reading before your first order.

Storage and reconstitution

Most peptides arrive lyophilized and need bacteriostatic water to reconstitute. Reconstituted peptide should be refrigerated and used within a few weeks. Avoid freeze-thaw cycles, which destroy peptide integrity. See the Reconstitution guide for technique and the calculator.

Start low, go slow

Begin at the low end of any reported dose range. Many adverse reactions are dose-dependent and avoidable. If a peptide is new to your stack, introduce it alone — adding two new compounds at once makes attribution impossible.

Absolute contraindications worth knowing

Some categories cross-cut every peptide decision:

• Active malignancy or recent cancer history — growth-promoting peptides (GH secretagogues, IGF-1 axis) are contraindicated.
• Pregnancy or breastfeeding — almost no peptide has safety data in this population. Default to not using.
• Severe cardiovascular disease — GLP-1s and melanocortins have cardiovascular signals that require clinical oversight.
• Personal or family history of medullary thyroid cancer or MEN-2 — GLP-1s are contraindicated.
• Active autoimmune disease — immune-modulating peptides (thymic peptides, KPV) need clinical input.

When to talk to a clinician

If you have any active condition, peptides should be discussed with a clinician — preferably one familiar with the category. Telemedicine clinics that specialize in this space have multiplied; quality varies, vet carefully. See the Working with a clinician guide.