Side effects of taking GNC's Mega Men Extreme Athlete Vita Packs include constipation, diarrhea and an upset stomach. Some men experience serious side effects or have an allergic reaction, which includes rashes, itching and trouble breathing. GNC recommends taking this product under a doctor's supervision.
The GNC Mega Men dietary supplement is a multivitamin designed to support an active man's nutritional needs. It contains high amounts of minerals, vitamins and nutrients of which the U.S. Food and Drug Administration has recommended daily values. For example, Mega Men contains 500 percent of the FDA's recommended daily intake of calcium, and it contains 2,500 percent of the recommended daily intake of Vitamin B-6. Such large doses can result in side effects.
The inclusion of carnitine in GNC Mega Men can cause diarrhea. Carnitine supports the metabolism of food. Too much, and the body frequently passes liquid stool. The high levels of carnitine can also cause dizziness and headaches, two other common side effects of taking this multivitamin.
Many dietary supplements warn that high levels of vitamin B-12 can result in itching and rashes, and GNC Mega Men is no different, with more than 800 percent of the recommended intake of this vitamin.
High levels of vitamin B-5 can cause nausea. GNC Mega Men contains 500 percent of the recommended intake of this vitamin. Vitamin B-1 can also cause nausea, and GNC Mega Men has more than 3,300 percent of the daily recommended intake.