When nasal spray makes sense Choose nasal spray when: Severe needle phobia (can't overcome) Peptide proven effective nasally (PT-141, Semax) Convenience absolute priority Willing to pay 2-3x more for same effect Traveling frequently (easier to carry) Don't want injection marks Best candidates for nasal: PT-141 users (proven nasal efficacy) Semax/Selank users (designed for nasal) Needle-phobic individuals Infrequent users (as-needed dosing) Those who tried injection and hated it When injection is better Choose injection when: Want maximum efficacy Budget-conscious (2-3x less expensive) Using peptides designed for injection Need consistent results Long-term regular use planned Comfortable with needles (or can learn) Best candidates for injection: Growth hormone peptides (Ipamorelin, CJC-1295) Daily peptide protocols Cost-conscious users Those wanting proven delivery Comparison summary: Hybrid approach: Some use injection primarily Keep nasal spray for travel/convenience Example: Inject BPC-157 , nasal PT-141 Match delivery to peptide and situation See peptide injections guide for injection technique

Interestingly, the late vasodilation in response to prolonged sensory stimulation tends to be more specific to layer 4, the primary target of sensory inputs from the thalamus, compared to the early hemodynamic response 41,42
Andersson, Emmanuel Shapira, Biochemical and clinical response to hydroxocobalamin versus cyanocobalamin treatment in patients with methylmalonic acidemia and homocystinuria (cblC), The Journal of Pediatrics, Volume 132, Issue 1, January 1998, Pages 121-124, ISSN 0022-3476, Okuda K, Yashima K, Kitazaki T, Takara I
It is not an FDA-approved weight-loss medication