Background: Autism spectrum disorder (ASD) patients are increasingly turning to complementary and alternative medicine (CAM) as a method of treatment. This therapy includes hyperbaric oxygen therapy (HBOT), casein-free/gluten-free diet (CF/GF), vitamin D, and music therapy. Hyperbaric oxygen therapy (HBOT) may be used for autistic children to overcome cerebral hypoperfusion, and it has an anti-inflammatory effect. Casein free/ gluten-free diet has a good effect on autistic children by decreasing peptides resulting from the breaking down of these proteins. These peptides have a bad effect on the brain and cognitive functions. Vitamin D can relieve autism symptoms by repairing DNA mutations. Also, Vitamin D has anti-inflammatory and stimulates the immune system. More parents of autistic children use CAM therapies due to their safety and fewer side effects. CAM therapies need to be evaluated for their effectiveness in autistic children. Methods: This review compares several studies to determine the validity of these therapies and helps specialists decide in this regard. Results: Most of the studies support CAM therapies for relieving symptoms of autism, while few oppose these therapies. Conclusion: Complementary and alternative medicine are promising therapies and need more attention to prove their effectiveness.