In This Guide
Why Interaction Screening Matters
Most peptide researchers focus on what a compound does in isolation. Fewer systematically consider what it does in combination with other compounds they are already taking — whether that is other peptides, prescription medications, or common supplements.
Peptides are pharmacologically active compounds. They bind to specific receptors, modulate hormonal axes, affect metabolic pathways, and interact with the same biological systems that prescription medications target. The fact that they are not FDA-approved drugs does not mean they are pharmacologically inert or that interactions are impossible.
Interaction screening is not about finding reasons not to use a compound. It is about understanding the full pharmacological context of your protocol — so that if something unexpected happens, you have a framework for understanding why.
Interaction Severity Categories Explained
Contraindicated
Known or strongly theoretical interactions that present meaningful safety risk. These combinations should not be used without direct medical supervision.
Caution
Interactions with meaningful pharmacological basis that require careful consideration, dose adjustment, or monitoring. Not necessarily prohibited but warrant attention.
Monitor
Theoretical interactions based on shared mechanisms or pathways. Plausible but not confirmed. Monitor for additive or antagonistic effects.
No Known Interaction
No published or theoretical interaction identified based on current literature. Does not guarantee safety — absence of evidence is not evidence of absence.
Types of Interactions the Tool Checks
Pharmacodynamic
Compounds acting on the same receptor or biological pathway — producing additive, synergistic, or antagonistic effects on the same physiological endpoint.
Pharmacokinetic
Compounds that affect each other's absorption, distribution, metabolism, or excretion — altering effective concentrations or duration of action.
Receptor Competition
Compounds competing for the same binding site — one may block or reduce the effect of the other, or displace it from the receptor.
Hormonal Axis
Compounds affecting the same hormonal axis (GH, HPG, HPA) — with potential for complex feedback interactions, particularly when combining secretagogues with exogenous hormones.
The Most Important Peptide Interactions to Know
The following are among the most clinically relevant interactions in the Compound Review database. This is not an exhaustive list — use the Interaction Checker for a complete screen of your specific protocol.
Both GH secretagogues and insulin affect glucose metabolism. Combined use requires monitoring of blood glucose, particularly around administration timing.
BPC-157 modulates COX pathways and prostaglandin signaling. Theoretical interaction with NSAIDs — may alter anti-inflammatory efficacy in either direction.
PT-141 can cause transient blood pressure changes. Combined use with antihypertensives requires monitoring.
Kisspeptin stimulates the HPG axis. Combined use with exogenous androgens creates complex hormonal feedback interactions.
GHK-Cu has theoretical effects on tissue remodeling pathways. Theoretical interaction with anticoagulants — monitor coagulation parameters.
Epithalon has reported immunomodulatory effects. Combined use with immunosuppressants may produce complex immune interactions.
How to Use the Interaction Checker
Add all compounds in your protocol
Include every compound you plan to use — peptides, prescription medications, OTC drugs, and relevant supplements (especially hormones, blood thinners, diabetes medications, and blood pressure medications).
Review the interaction matrix
The tool generates a matrix showing every compound-pair combination and its interaction level. Start with any 'Contraindicated' or 'Caution' flags.
Read the interaction detail
Click any flagged interaction to read the full detail: mechanism, evidence basis, severity rationale, and recommended action (avoid, monitor, adjust dose, consult provider).
Consult a healthcare provider for flagged interactions
Any 'Contraindicated' or 'Caution' interaction should be discussed with a qualified healthcare provider before proceeding. The tool provides the information — a provider helps you interpret it in the context of your individual situation.
Save your screen to your research log
The interaction screen can be saved to your Trial Tracker as part of the protocol setup documentation — creating a record that you performed due diligence before starting.
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Shop Purgo Labs — Use Code HEALTH for 20% OffFrequently Asked Questions
What is the Compound Review Interaction Checker?
The Interaction Checker is a free tool that screens for known and theoretical interactions between research peptides and other compounds — including other peptides, prescription medications, over-the-counter drugs, and common supplements. It draws on published pharmacological literature and flags interactions by severity (contraindicated, caution, monitor, or no known interaction).
What types of interactions does the tool check?
The tool checks for four categories: (1) pharmacodynamic interactions — compounds that act on the same receptor or pathway and may produce additive, synergistic, or antagonistic effects; (2) pharmacokinetic interactions — compounds that affect each other's absorption, distribution, metabolism, or excretion; (3) receptor competition — compounds that compete for the same binding site; and (4) hormonal axis interactions — compounds that affect the same hormonal axis (e.g., two GH secretagogues used simultaneously).
Is the Interaction Checker a substitute for medical advice?
No. The Interaction Checker is a research reference tool, not a medical device or clinical decision support system. It is designed to help researchers identify known and theoretical interactions that warrant further investigation or discussion with a healthcare provider. It does not account for individual patient factors, comorbidities, or the full complexity of clinical pharmacology.
What does 'theoretical interaction' mean?
A theoretical interaction is one that is plausible based on known pharmacology but has not been directly studied or confirmed in published literature. For example, two compounds that both stimulate GH release via different mechanisms (e.g., CJC-1295 and Ipamorelin) have a theoretical additive interaction on GH secretion — this is widely used in practice as a stack, but the combined effect has not been formally studied in a controlled trial. The tool flags these as 'theoretical — monitor' rather than 'contraindicated'.
What are the most important interactions to know about?
The highest-priority interactions are: (1) GH secretagogues + insulin — both affect glucose metabolism and the combination requires careful monitoring; (2) peptides affecting the HPG axis (Kisspeptin, PT-141) + exogenous sex hormones — complex hormonal interactions; (3) BPC-157 + NSAIDs — BPC-157 may modulate COX pathways, potentially affecting NSAID efficacy; (4) any peptide + anticoagulants — some peptides have theoretical effects on platelet aggregation or coagulation factors.
How often is the interaction database updated?
The interaction database is reviewed and updated quarterly as new research is published. Each interaction entry includes its evidence basis (published study, case report, theoretical/mechanistic) and the date it was last reviewed.
Can I check interactions between two peptides?
Yes. The most common use case is checking peptide-peptide interactions — particularly for stack protocols. The tool supports checking any combination of compounds in the Compound Review library against each other, as well as against a growing list of common medications and supplements.