ADVERSE REACTIONS Nystatin is well tolerated even with prolonged therapy. Oral irritation and sensitization have been reported. (See PRECAUTIONS: General . ) Gastrointestinal Diarrhea (including one case of bloody diarrhea), nausea, vomiting, gastrointestinal upset/disturbances. Dermatologic Rash, including urticaria has been reported rarely. Stevens-Johnson syndrome has been reported very rarely. Other Tachycardia, bronchospasm, facial swelling, and nonspecific myalgia have also been rarely reported.