Phenothiazine is primarily used in the pharmaceutical industry as a precursor for the synthesis of various antipsychotic drugs, such as chlorpromazine, which are effective in treating psychiatric disorders like schizophrenia and bipolar disorder. Its derivatives also exhibit antihistaminic and antiemetic properties, making them useful in managing allergies and preventing nausea and vomiting. In veterinary medicine, phenothiazine is employed as an anthelmintic to treat parasitic worm infections in livestock. Additionally, it serves as an antioxidant in the rubber and plastic industries, helping to prevent degradation caused by oxidation. Its ability to inhibit certain chemical reactions also makes it a valuable component in some industrial applications, such as stabilizers and corrosion inhibitors.