Most remedies come with side effects. You have to exchange your stuffy nose for drowsiness or your depression for headaches and diarrhea. With turmeric, you don't really have to worry about that. Taken in moderation, there are very few negative side effects, if any.
With that being said, if you were to take too much turmeric your body might react adversely, but you'd have to take massive amounts in order for that to happen. There is also a possibility that you could be allergic to turmeric, so be careful if you're trying it for the first time. You might want to rub some on your skin and see if a rash develops before ingesting it. An allergic reaction isn't the only possible negative side effect. For persons being chemically treated for diabetes and high blood pressure, turmeric could increase the strength of your medication, which could be dangerous. Also, turmeric can interact with other medications, dietary supplements and herbs. So be sure to check with your doctor of pharmacist before inserting turmeric into your daily regimen.
Though the FDA has yet to weigh in on the use of turmeric, a similar commission based out of Germany has stated that turmeric is only dangerous for people with biliary obstruction [source: Mother Nature]. It has also been advised that people with gastrointestinal problems like ulcers and gallstones should shy away from turmeric and if you have a sensitive stomach, it may upset you. Studies have also shown that extraordinary amounts of turmeric can damage white and red blood cells. However, the amount of turmeric you would have to consume to make this happen is great, making it very unlikely.
While more research needs to be done regarding turmeric and its possible side effects, you might want to stay away from it if you have blood-clotting issues or if you're pregnant [source: Tattva's Herbs]. There is no hard evidence to support negative effects in regards to either condition, but the anti-inflammatory nature of turmeric means it could adversely affect blood-clotting disorders and the effects on pregnancy and nursing are completely unknown.