Here are links to some studies on the value of Neem.
Healing Skin Issues:
https://www.ncbi.nlm.nih.gov/pubmed/24851844 A plant-derived wound therapeutic for cost-effective treatment of post-surgical scalp wounds with exposed bone. CONCLUSION: This retrospective, non-controlled analysis supports ONE as a simple-to-use and safe treatment option for scalp wounds with exposed bone. Treatment costs compare favorably to those published for other treatment modalities.
https://www.ncbi.nlm.nih.gov/pubmed/23835719 Neem (Azadirachta indica): prehistory to contemporary medicinal uses to humankind.
https://www.ncbi.nlm.nih.gov/pubmed/26195902 Effect of Neem oil and Haridra on non-healing wounds. CONCLUSION: Topical use of Neem oil and oral use of Haridra powder capsule used in combination were found effective for chronic non-healing wounds.
https://www.ncbi.nlm.nih.gov/pubmed/16900389 Efficacy of neem seed extract shampoo on head lice of naturally infected humans in Egypt
https://www.ncbi.nlm.nih.gov/pubmed/21484346 Ovicidal effects of a neem seed extract preparation on eggs of body and head lice.
https://www.ncbi.nlm.nih.gov/pubmed/20461406 The efficacy of neem seed extracts (Tre-san, MiteStop on a broad spectrum of pests and parasites
https://www.ncbi.nlm.nih.gov/pubmed/27687478 Neem toward the idea insecticide
https://www.ncbi.nlm.nih.gov/pubmed/27552943 Neem cake as a promising larvicide and adulticide against the rural malaria vector Anopheles culicifacies
https://www.ncbi.nlm.nih.gov/pubmed/27178630 Ethnobotanical uses of neem (Azadirachta indica A.Juss.
https://www.ncbi.nlm.nih.gov/pubmed/21695566 Observations on effects of a neem seed extract (MiteStop®) on biting lice (mallophages) and bloodsucking insects parasitizing horses.