Human hair serves a biological purpose of protecting the scalp, as well as physical attractiveness to the perception of beauty. Hair loss, graying of hair, dandruff and other conditions affecting hair conditions can be distressing to patients, as hair condition is often considered important in people’s own assessment of physical beauty. Different hair types can benefit from different treatment methods to promote hair health and growth. External factors like exposure to the sun and smoking, dietary factors including malnutrition of essential fatty acids and vitamins, and chemicals applied to the hair and scalp in shampoos and other treatments can all cause damage to existing hair and impair hair growth. Specific chemicals found in many shampoos, including antimicrobial agents, surfactants and preservatives, can all impair different aspects of hair health. In this review, we aim to discuss the main hair issues, such as hair loss, followed by the safety assessments of selected ingredients in shampoo, and possible nourishment for scalp improvement. This review highlights areas of disagreement in the existing literature, and points to new directions for future studies. Key conclusions include the carcinogenic chemicals to avoid, alternatives of such ingredients, and scalp nourishing treatments with micronutrients.