Noteworthy:  Many online sources sell an ineffective product.  Also, peptides are fragile by nature and are not effective when they are taken orally (pills, shakes, etc) because they will be broken down by the digestive process. Instead, peptides are mixed with bacteriostatic water and then injected under the skin with an insulin needle. Peptide injections in this manner are nearly painless and have clinically proven effectiveness.
Research in the early 1960s showed that in rats, administration of α-MSH caused sexual arousal, and work on this continued in many labs up through the 1980s, when scientists at University of Arizona began attempting to develop α-MSH and analogs as potential sunless tanning agents, and synthesized and tested several analogs, including melanotan-I and melanotan II.[6][9]
In regards to interventions, one study in treatment resistant depressed persons that combination therapy of 5-HTP with Carbidopa noted that 43 out of 99 (43.4%) patients improved with an average 200mg (variable 50-600mg) dosage of 5-HTP.[24] It has been noted[25] that since Cardidopa is a peripheral decarboxylase inhibitor that can prevent metabolism of monoamines including serotonin[26] that these results are unlikely to reflect monotherapy with 5-HTP, despite being within the 30-45% range sometimes seen with the placebo effect.[25][27]
But Carter and other scientists are concerned by reports from the physicians and parents of children with autism spectrum disorder who say that they are already using oxytocin off-label — before it has been thoroughly tested. “We do not understand how the hormone works yet, or have enough information about what happens when it's given repeatedly,” Carter says. “This is not a molecule that people should be self-administering or playing with.”

5-HTP is sometimes taken by people coming down from MDMA to relieve post-MDMA dysphoria.[8] As 5-HTP is a necessary precursor for the brain to produce more serotonin, and MDMA use depletes a person's natural serotonin levels, it is believed that taking 5-HTP after consuming MDMA will speed up serotonin production. DanceSafe claims that the anecdotal evidence is widespread and that the theory is physiologically reasonable.[9] Backing up this approach is research conducted by Wang, et al.  in 2007, which observed that MDMA-induced depletions of 5-HT (serotonin) were restored in rats after administration 5-HTP, and suggested that this approach might be clinically useful in abstinent MDMA users.[8]