James Duke discusses contra-indications for turmeric in his book Dr. Duke’s Essential Herbs.  “I once thought it hard to imagine that anyone would eat enough turmeric to experience significant side effects, but I’ve since heard from one cancer survivor who had trouble taking it in food and finds the standardized capsules much easier.  There are some suggestions in medical literature that people with gastrointestinal problems such as gallstones, stomach ulcers, hyperacidity, or bile duct obstructions shouldn’t eat large amounts of turmeric, although I suspect these cautions may have been overstated.  The German E Commission (a panel of experts roughly equivalent to the U.S. Food and Drug Administration) has advised against turmeric only for those people with biliary obstruction.  Apart from this, there’s some evidence that having too much turmeric may cause stomach irritation in people who are sensitive to it.  The irritation may be merely annoying, or it could lead to ulcers in supersensitive people.  Eating very large amounts of turmeric could potentially damage white and red blood cells.  As a practical matter, however, there is little likelihood that anyone would ever ingest enough to make this happen.”

Michael Tierra says the following for contraindications: “Turmeric should be avoided during pregnancy.  It should not be used when there is anemia (blood deficiency) with signs of stagnation of blood or qi.” (40)

Daniel Mowrey says the following about toxicity: “No toxicity has been observed at recommended dosages.  In exceedingly high amounts, it has been observed to inflame the mucus linings of the stomach.  Since this reaction is similar to that of cayenne on “innocent” tissue, it is possible that the stomach lining would adapt to the presence of turmeric over time, eventually exhibiting no inflammation at all to even very high doses.” (28)

Michael Murray’s comments on toxicity of turmeric are as follows: “Toxicity reactions have not been reported at standard dosage levels.  The oral LD50 (50 percent lethal dose) has not been established, because curcumin fed to mice, rats, guinea pigs, and monkeys at 2.5 grams per kilogram, an sodium curcuminate fed to rats at 3.0 grams per kilogram, resulted in neither mortality nor genetic damage.  At high doses curcumin or turmeric may damage the gastrointestinal system because curcumin at doses of 100 milligrams per kilogram body weight was ulcerogenic in rats. (30)

Kai Kaholokai gives the following precautions: acute jaundice and hepatitis, high pitta, and pregnancy. (44)