Randomized controlled trials typically do not report adverse effects associated with consumption of tart cherry juice. Case reports of acute kidney injury from daily consumption of cherry juice concentrate, including black cherry concentrate[1] and an unspecified cherry juice concentrate,[2] have been reported in people with chronic kidney disease (CKD). Whether similar issues in people with CKD could carry over to tart cherry juice intake is unclear, but plausible.
The mechanism by which the polyphenols in cherry juice concentrate reduce inflammation (i.e., by inhibiting cyclooxygenase enzymes) may also reduce kidney function in people with CKD.[1][2] Because tart cherry juice concentrate is rich in many of the same polyphenols as other cherry juice concentrates, it could also potentially be harmful for people with CKD.
Another potential drawback of tart cherry juice is its carbohydrate content. It contains polyols,[3] a specific type of carbohydrate that can be harmful to people with irritable bowel syndrome.[4] A cup of tart cherry juice contains about 130 kcal, so it can theoretically contribute to weight gain, though studies have reported that supplementation with tart cherry juice does not affect BMI or fat mass.[5]
High doses of antioxidants can also impair exercise-induced adaptations,[6] so long-term supplementation with tart cherry juice could be detrimental for athletes, particularly in the off-season, when the goal is to maximize exercise-induced adaptations. However, direct evidence is needed to determine whether the commonly consumed dose of tart cherry juice is large enough to have this effect.