The U.S. Food and Drug Administration does not strictly regulate herbs and supplements. There is no guarantee of strength, purity or safety of products, and effects may vary. You should always read product labels. If you have a medical condition, or are taking other drugs, herbs, or supplements, you should speak with a qualified healthcare provider before starting a new therapy. Consult a healthcare provider immediately if you experience side effects.


Avoid with known allergy or sensitivity to creatine.

Although creatine is a common dietary component (in meat and fish), allergy to creatine has been reported. Mild asthma-like symptoms after chronic consumption of creatine (20 grams daily for five days followed by 10 grams daily for 51 days) has occurred.

Side Effects and Warnings

Creatine is likely safe when used long-term.

Creatine may lower blood sugar levels. Caution is advised in people with diabetes or hypoglycemia, and in those taking drugs, herbs, or supplements that affect blood sugar. Blood glucose levels may need to be monitored by a qualified healthcare professional, including a pharmacist, and medication adjustments may be necessary.

Creatine may cause high blood pressure. Caution is advised in people taking drugs or herbs and supplements that raise blood pressure.

Use cautiously in people with deep vein thrombosis, electrolyte disorders or imbalances, gastrointestinal disorders, irregular heartbeat, kidney stones, liver disease, migraines, musculoskeletal disorders, neurological dysfunction, neuromuscular disorders, orthostatic hypotension (low blood pressure upon standing),participating in mass-dependent activities such as running, swimming and gymnastics, psychiatric disorders, seizures, skin disorders, and athletes who may combine dehydration regimens (diuretics, sweating).

Use cautiously in people taking agents cleared through the kidneys or agents toxic to the kidneys including (but not limited to) aminoglycosides (parenteral), gallium nitrate, tacrolimus, and valacyclovir; agents that increase urination; agents toxic to the liver; caffeine and caffeine-containing medications; central nervous system (CNS) depressants; chemotherapy; cholesterol lowering agents; cimetidine; digoxin; nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen and naproxen; probenecid; and trimethoprim.

Avoid in people with impaired kidney function, dehydration, or bipolar disorder. Avoid in combination with ephedra. Avoid with known allergy or sensitivity to creatine.

Creatine may also cause abnormal heart rate, additive effects of chemotherapy or CNS depressants, aggression, altered serum creatinine levels, anorexia, anxiety, asthmatic symptoms, burping, change in appetite, changes in markers of liver function, combative behavior, confusion, constipation, decrease in cellular stores of creatine, dehydration, depression, diarrhea, drowsiness, electrolyte imbalances, elevated liver enzymes, fainting, fever, headaches, heat intolerance, high blood pressure, hypercarbia (excess carbon dioxide in blood), hyperthermia, increased cortisol, increased formaldehyde production, increased creatine in the urine, increased insulin levels, increased risk of kidney toxicity, increased risk of side effects from caffeine, increased symptoms of deep vein thrombosis, inflamed kidneys, inflammation of stomach and small intestine, irritability, ischemic stroke, jaundice, kidney dysfunction, light-headedness, liver injury, lower blood sugar, mania or hypermania, metabolic acidosis, muscle cramping or pain, myopathy (muscle disease), nausea, nervousness, pressure of the shins, psychosis, reduced blood volume, reduced phosphocreatine synthesis, rhabdomyolysis (muscle breakdown), seizures, skin rashes, stomach discomfort, swollen limbs, thirst, vomiting, water retention, weight gain, worsening sleep problems, yellowing of the skin.

The U.S. Food and Drug Administration (FDA) has advised consumers to consult their physicians before using creatine. There is concern that athletes may exceed recommended doses; under these conditions the side effects are unclear.

Note: There is limited systematic research on the safety, pharmacology, or toxicology of creatine. Individuals using creatine, including athletes, should be monitored by a qualified healthcare professional. Heat intolerance, fever, dehydration, reduced blood volume, or electrolyte imbalances (and resulting seizures) may occur.

Pregnancy and Breastfeeding

There is a lack of sufficient data on the use of creatine during pregnancy or lactation.

In theory, creatine supplementation of nursing mothers may help to avoid creatine deficiency syndromes, but studies focusing on this are lacking. Creatine supplementation is suggested to be avoided unless it is prescribed by a healthcare professional.

This evidence-based monograph was prepared by The Natural Standard Research Collaboration