Pubic hair growth is not normal for a 7 1/2 year old boy, and may be related to precocious puberty, i.e. symptoms caused by excessive secretion of androgens. Due to individual differences, there is no fixed value for the length of pubic hair in boys. Most boys experience the above symptoms around the age of 9 to 10 years old, and if pubic hair growth occurs at the age of 7.5 years old, it may belong to precocious puberty. The causes of precocious puberty are quite varied, and may be related to exposure to chemicals and excessive consumption of medications such as health supplements. It is necessary to bring the child to the hospital for examination of sex hormones, bone age, and MRI of the skull. Seven and a half year old boy long pubic hair is recommended to consult as soon as possible, by a professional physician to carry out a comprehensive judgment, if it is determined to be precocious need to carry out targeted treatment, do not use their own drugs.