There are many symptoms and decreased body functions due to zinc deficiency. It may cause slowed growth or slow sexual development in the pubertal years. Lowered resistance, fatigue, and increased susceptibility to infection may occur with zinc deficiency, which is related to a decreased cellular immune response. Sensitivity and reactions to environmental chemicals may be exaggerated in a state of zinc deficiency as many of the important detoxification enzyme functions may be impaired.

Children with zinc deficiency may show poor appetite and slow development, have learning disabilities or poor attention spans, and in later years have acne and decreased sexual development. Dwarfism and a total lack of sexual function may occur with serious zinc deficiency. Fatigue is common.

Acute deficiency may cause hair loss or thinning, dermatitis, and decreased growth. Both poor appetite and digestion are also experienced by adults with zinc deficiency. Loss of taste sensation may occur, as can brittleness of the nails or white spots on the nails, termed leukonykia. These and most other symptoms can be corrected with supplemental zinc. Sulfur may be helpful as well. Skin rashes, dry skin, and delayed healing of skin wounds or ulcers may result from zinc deficiency, and stretch marks, called striae, are also produced by this condition. Zinc and copper are both needed for cross-linking of collagen, and when they are low, the skin tissue may break down.

Zinc deficiency may cause delayed menstruation in teenage females or, in later years, cause menstrual problems. In addition to zinc, vitamin B6 often also helps correct this. Females on birth control pills usually have elevated copper levels and need additional zinc and B6. When zinc is further reduced by the increased copper, depression is more likely, a common side effect of birth control pill use. Morning sickness in pregnancy may result from low zinc and B6 levels, and supplementing these nutrients may help reduce symptoms.

Male teenagers with low zinc have delayed or absent sexual development. Sterility may result from zinc deficiency; when it is caused by testicular degeneration, it may be irreversible. Subtle zinc deficiencies may be responsible for male growth lag in puberty. Even in sexually developed males, low zinc levels have been correlated with a decrease in testosterone levels and a lower sperm count. Prostate problems are more prevalent with zinc deficiency.

Birth defects have been associated with zinc deficiency during pregnancy in experimental animals. The offspring showed reduced growth patterns and learning disabilities. In humans, children with zinc deficiency have decreased intelligence and erratic behavior. With zinc treatment, the IQ and behavior may both improve if the problem is related to zinc deficiency.