Sports supplements such as creatine and those containing diuretics or stimulants may be used to improve muscle mass, increase energy, reduce water retention or enhance weight loss. According to the Mayo Clinic, because supplements are not regulated by the Food and Drug Administration (FDA) or tested for safety and effectiveness, they frequently contain contaminants. Though short-term use of sport supplements may provide benefits, digestive side effects may occur that may inhibit athletic performance. For best results, a doctor's guidance is suggested.
Abdominal Cramps
Sports supplements may cause painful cramps in the stomach muscles. Wrestlers and body builders are known to utilize diuretics, which flush fluid from the body, to compete within a lower body weight level or to reduce bloating that conceals muscle definition. According to the Mayo Clinic, excessive intake of diuretics may cause dehydration and lead to severe stomach cramps. Creatine, a popular over-the-counter supplement used to promote muscle growth and delayed muscle fatigue, also may trigger abdominal cramps.
Nausea
Numerous sports supplements are known to cause nausea, the feeling that precedes vomiting. According to the Mayo Clinic, nausea is a potential side effect of creatine. Athletes who take supplements containing stimulants such as caffeine also may experience nausea. Although modest caffeine intake may not cause adverse effects, excessive intake, or more than 300 milligrams, increases risk for nausea and other side effects, according to the "New York Times Health Guide". Dietary supplements that contain other stimulants such as ginseng or guarana or contaminants also may trigger nausea.
Diarrhea
Diarrhea, or loose, frequent stools, may stem from sport supplement use. Both creatine and caffeine-containing stimulants have been known to cause diarrhea. In many cases, abdominal cramps accompany diarrhea. People taking diuretics along with creatine or stimulant-based supplements may suffer serious complications including dehydration and electrolyte imbalances if diarrhea occurs. Contaminated supplements also may cause diarrhea.
Vomiting
Vomiting may occur in response to various sports supplements. According to the "New York Times Health Guide", stopping caffeine use after routine use or dependency may cause withdrawal symptoms, such as vomiting. Some sports supplements contain vitamins and minerals. Sports supplements that contain the mineral iron may increase risk for vomiting, because excessive intake of the nutrient in supplement-form is known to cause toxic effects. Risk of iron-toxicity and vomiting increases if supplements are taken on an empty stomach, according to the Office of Dietary Supplements. Supplements containing contaminants also may trigger vomiting.
