The most common cranberry side effects are mild stomach upset and diarrhea, and drinking too much juice may result in the formation of kidney stones because of the high levels of oxalate in the berry. It has been found that people who have an allergy to aspirin may also be allergic to cranberry and because most juices are sweetened, diabetics should ensure artificial sweeteners have been used. There may also be negative interactions with drugs like those taken to thin the blood and with some that are processed by the liver.
The health benefits of cranberries have long been recognized by nutritional experts. Antioxidants called phenols are present in the fruit and these aid in the prevention and reparation of damaged cells. The anti-bacterial properties of the cranberry are enlisted to prevent and treat stomach ulcers and urinary tract infections. The fruit can be eaten fresh or dried, juice is also available as are cranberry supplements.
Gastrointestinal upset and diarrhea are the most common cranberry side effects reported, but this is usually associated with an excessive intake of the juice or supplement. In small doses, there should be no such reaction. Aspirin and cranberries are similar in that they both contain salicylic acid, which means that if you are allergic to one, chances are you will be allergic to the other. While drinking a small amount of cranberry juice should be safe, supplements should be avoided as they contain more concentrated amounts of the fruit.
One of the cranberry side effects is due to the fact that cranberries contain high levels of oxalate, a chemical compound that combines with calcium to form kidney stones. This would necessitate the drinking of an average of one liter of cranberry juice a day or the taking of supplements over a long period of time, but if there is a family history of kidney stones, then it is probably best to avoid cranberries just in case.
Cranberry may also have a negative interaction with some drugs. Warfarin, which is used to slow blood clotting, may remain in the body for longer and increase the chances of bruising and bleeding when combined with cranberry intake. Other medications which interact with cranberry include those that are changed and broken down in the liver. Cranberry side effects in this case involve decreasing how rapidly the medications are broken down which means the effects and side effects of the drugs may increase. Ibprofen, diazepam such as in Valium, and diclofenac such as in Voltaren are some examples of the medications affected by cranberry intake in this way.