Peptide Interaction Checker
Check if two peptides are safe to combine. Get compatibility ratings, timing recommendations, and safety warnings.
Understanding Peptide Interactions
When using multiple peptides at the same time, understanding how they interact is critical for both safety and effectiveness. Some peptides amplify each other's effects through complementary mechanisms, while others compete for the same pathways or produce overlapping side effects that can increase risk. Checking interactions before starting a stack is one of the most important steps in building a responsible peptide protocol.
Peptide interactions generally fall into four categories: synergy, safe, caution, and avoid. Synergistic combinations work better together than alone — the peptides enhance each other through different but complementary mechanisms. Safe combinations have no known interactions and can be used concurrently without concern. Caution combinations require awareness of specific factors like blood sugar monitoring or timing separation. Avoid combinations should never be used together due to overlapping mechanisms or increased risk.
Timing is often as important as the combination itself. Many peptides have specific windows when they are most effective — GH secretagogues work best before bed on an empty stomach, fat-loss peptides are most effective while fasted, and healing peptides like BPC-157 can be injected at any time. Stacking two peptides that both require a fasted state means you need to plan your injection schedule carefully to avoid conflicts. New to peptides? Start with our beginner guide or take the peptide quiz.
How to Use This Tool
- 1.Select the first peptide from the dropdown. This is one of the two peptides you are considering combining in your stack.
- 2.Select the second peptide. The dropdown automatically excludes the peptide you already selected to prevent checking a peptide against itself.
- 3.Click "Check Interaction" to see the compatibility rating, timing recommendation, and additional safety notes for this combination.
Interaction Levels Explained
Frequently Asked Questions
Can you mix two peptides in the same syringe?
Some peptides can be mixed in the same syringe for convenience. BPC-157 and TB-500 are a well-known example — they are chemically compatible and can be drawn into the same syringe. CJC-1295 and Ipamorelin can also share a syringe. However, not all peptides are compatible when mixed directly. GLP-1 agonists like semaglutide should generally be injected separately. When in doubt, use separate syringes and different injection sites.
What does synergy mean for peptide combinations?
Synergy means that two peptides work better together than either one alone. They enhance each other's effects through complementary mechanisms. For example, BPC-157 promotes blood vessel formation while TB-500 supports cell migration — together they accelerate healing beyond what either peptide achieves individually. Synergistic stacks are considered optimal combinations.
Is a caution rating dangerous?
A caution rating does not mean the combination is dangerous. It means there are specific considerations to be aware of, such as monitoring blood sugar or separating injection timing. Most caution-rated combinations can be used safely with proper planning and awareness. Always monitor your body's response and consult a healthcare provider if you have pre-existing conditions.
What are the most dangerous peptide combinations?
The most important combinations to avoid are stacking two GLP-1 agonists together (e.g. semaglutide + tirzepatide, or semaglutide + retatrutide). These share overlapping mechanisms and combining them can cause severe gastrointestinal side effects and increase the risk of pancreatitis. Similarly, HGH Fragment 176-191 and AOD-9604 are redundant since AOD-9604 is derived from the same HGH fragment — using both provides no additional benefit.
How should I time multiple peptide injections?
Timing depends on the specific peptides. GH secretagogues like CJC-1295 and Ipamorelin work best before bed on an empty stomach. HGH Fragment and AOD-9604 are most effective in the morning while fasted. BPC-157 and TB-500 can be injected at any time, ideally near the injury site. GLP-1 agonists like semaglutide are injected once weekly at any time. When stacking, separate peptides that compete for the same pathways by at least 8 to 12 hours.
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