Start from the full list
Whatever you are taking — prescriptions, over-the-counter products, supplements, herbal preparations — belongs on one list your prescriber can see. People consistently under-report supplements because they feel like food rather than medicine.
They are not food. Some carry genuine interaction risk.
The interactions that matter most here
Methylene blue has meaningful monoamine oxidase inhibitory activity and should not be combined with SSRIs, SNRIs, MAOIs or other serotonergic agents. This is the clearest contraindication in a typical peptide supplement range and it is not negotiable.
Beyond that: products affecting clotting matter around any procedure; high-dose botanicals can affect drug metabolism; and anything sedating compounds with anything else sedating.
Stacking sensibly
Introduce one thing at a time and leave enough space to attribute an effect. Starting three products the same week and then trying to work out which caused what is a guaranteed waste of money.
Set a review date. If you cannot tell whether something is doing anything after a reasonable trial, that is information.
Timing and absorption
Follow the directions on each product rather than taking everything at once for convenience. Some products specify an empty stomach; some are better tolerated with food; some are better in the evening.
Where instructions conflict with your routine, ask rather than improvising a compromise.
During an active protocol
While you are titrating a prescription protocol, adding new supplements makes attribution harder. If you can, hold the supplement changes until the prescription dose is stable.
And tell your regular physician. This is educational content, not medical advice, and your prescriber's instructions govern.