Vitamin A palmitate is a more stable, synthetic version of the essential nutrient vitamin A joined to palmitic acid. Vitamin A palmitate is the form used to fortify foods and skin moisturizers. The U.S. Food and Drug Administration says it is generally regarded as safe. The FDA reports the lowest dose for side effects is a total vitamin A intake of 700 to 1,000 international units per kilogram per day over several months. In comparison, the recommended dietary allowance for adults is 50 international units per kilogram per day. The typical Western diet does not approach toxic levels of vitamin A unless large doses are taken as supplements.
Vitamin A in its natural form of retinol is a common ingredient in topical creams marketed as wrinkle reducers or acne medications. In high doses taken by mouth, it causes dry, itchy or peeling skin on the lips and palms. Yellow-orange patches may appear on the soles of the feet, palms of the hands or on the skin around the nose and lips. Skin can become increasingly sensitive to sunlight at high doses. Hair loss is another side effect of taking toxic levels of total vitamin A.
The severity of pain or illness experienced with ingesting high amounts of vitamin A varies with the dose. General weakness, joint and bone pain ranges from mild to disabling.
People taking high doses of vitamin A experience nonspecific symptoms. The National Institutes of Health Office of Dietary Supplements notes that general feelings of discomfort including headache, irritability, dizziness, fatigue and unusual excitability are reported. Double vision and convulsions are rare events that should be reported immediately to a doctor.
Stomach pain, loss of appetite, nausea and vomiting are common side effects of ingesting large amounts of vitamin A.
The NIH Office of Dietary Supplements reports that vitamin A is stored in the liver and excess intake can enlarge the liver and cause liver damage. People with liver disease risk developing intrahepatic cholestasis, a condition where bile can no longer flow into the intestines. Symptoms include intense itching--especially of the feet and hands, dark colored urine, light colored stool and increased frequency of urination or amount of urine passed.
Pregnant women who consume toxic levels of vitamin A increase the risk of birth defects in their unborn child. The FDA reports that laboratory animals fed high doses of vitamin A experience abortions or malformation of the central nervous system of the developing fetus. Vitamin A is excreted in breast milk. Infants exhibit a bugling fontanel or soft spot and brain pressure from ingesting high levels of vitamin A.