Potentially Beneficial Effects

In response to resistance exercise, ornithine and arginine supplementation significantly increases growth hormone and insulinlike growth factor-1, or IGF-1, according to a double-blind study. Growth factor is a protein molecule capable of stimulating tissue growth, and IGF-1 regulates carbohydrate metabolism. These increases have the potential benefit of increasing insulin sensitivity and boosting muscle mass. The "Journal of Strength and Conditioning Research" published this study in April 2010.

Digestive System Upset

Sensitivity to supplements is highly individual, and the side effects some people experience may not occur in others. Scientists evaluated the potential side effects of taking ornithine and related amino acids and discovered that tolerance varied widely. Single doses caused nausea, vomiting or diarrhea in some people but not others, according to the study. The results were published in the June 2007 edition of the "The Journal of Nutrition." If you experience these side effects, they may go away as your tolerance builds up, or you may need to lower your dose until your body adjusts.

Amino Acid Disturbance

In food, amino acids are found in groups, not separately. Taking single amino acids is controversial because your body works to keep them in balance. In theory, supplementing with any one of them singly, including ornithine, may disrupt this balance. There isn't much research into this potential side effect. However, the "European Journal of Nutrition" published an interesting finding in 1999. Researchers found that regularly taking arginine resulted in a reduction of total amino acids levels in the body. This suggests that, in trying to keep amino acids balanced, your body responds by reducing the overall levels. Athletes may find this side effect undesirable since the goal is to increase amino acid levels.

Risk of Dehydration

Taking ornithine, or any other amino acid for that matter, increases the production of the waste product nitrogen. Your body excretes nitrogen through urine, and taking ornithine increases urine production and electrolyte loss. This side effect can lead to dehydration and electrolyte imbalance if you're not careful. While taking ornithine, it's crucial to drink plenty of water and eat lots of vegetables and fruits to replace minerals. Signs of dehydration include muscle cramps, headache, fatigue and dry mouth.