We don’t know much about how graviola affects the body. But some researchers are concerned that particular chemicals present in graviola may cause nerve changes and movement disorders when taken in large amounts. The nerve changes may cause symptoms similar to Parkinson's disease. Laboratory research has found that some substances in graviola cause nerve damage and that these substances can cross into the brain from the bloodstream.
One research study has shown that people in the Caribbean who had large amounts of graviola in their diet were more likely to develop particular nerve changes and were also more likely to have hallucinations. It is unlikely that drinks or foods containing graviola could harm you when taken as part of a normal diet. But always talk to your doctor before taking any kind of complementary or alternative therapy.