Your IGF-1 probably didn't work because it wasn't renatured correctly. Other forums have posted nice semi-soft science threads that describe its reconstitution from lyophylized (free dried) powder. You need 100 mM acetic acid buffer acid to protonate the surface enough of this relatively small peptide to get 'untangled" from the protein glue it forms once water hit the concentrated mass.
Plus, you got fuckchops who think they know what they're doing when they use a peptide synthesizer. Don't purify the endproduct, you get these short shit sequences that are competitive binders for the same active sites as the long from IGF-1, 'cept that they don't work. Plus, your product did sit in not so good conditions in a hot environment before you made it up to use.
My guess: dirty product of questionable quality, improper reconstitution and potentially thermal damage, in that order. The lack of effective product would support the observation of a lack of the commonly reported headache side effect Why do you get headaches from IGF-1? It interacts with pro-inflammatory agents (cytokines and prostanoids) in various cells, including the muscles of the neck and head, and in brain, where mild neuralgia can be induced by inflammation at the base of the brain/spinal chord junction.
How do I know this? I worked in molecualr biology and protein biochemisry for many years.
The reason you aren't a creatine responder is that you haven't the proper ion control in your cells; that can be remedied. Plus, you may have been using a creatine form (monohydrate) that dimerized(forms polymers that are too big to be effectively transported into intestinal lumen) during commercial process drying (its sold as anhydrous crystalline form). I'd put my money on the dimerized form and also your aquaporin status, Mudge.
The headache comes from
