Decitabine Side effects:
Important things to remember about the side effects of Decitabine:
You will not get all of the side effects mentioned below.
Side effects are often predictable in terms of their onset, duration, and severity.
Side effects are almost always reversible and will go away after therapy is complete.
Side effects are quite manageable. There are many options to minimize or prevent them.
The following side effects are 
common (occurring in greater than 30%) for patients taking Decitabine:
Low blood counts. Your white and red blood cells and platelets may temporarily decrease. This can put you at increased risk for infection, anemia and/or bleeding, and may increase need for blood or platelet transfusions.
Fatigue
Fever
Nausea
Cough
Petechiae  (Tiny red dots on your skin, called petechiae [pe- TEEK- ee- ay].  Can occur with low platelet count.)
Constipation
Diarrhea
Hyperglycemia - high blood glucose levels
These are 
less common side effects for patients receiving Decitabine:
Headache
Difficulty sleeping
Swelling 
Low albumin 
Low magnesium 
Chills 
Low potassium 
Bruising 
Rash 
Low sodium 
Dizziness 
Generalized aches and pains
Cardiac murmur 
Poor appetite 
Sore throat 
Abdominal pain 
High bilirubin blood level
High potassium 
Mouth sores
Drowsiness 
Abnormal liver function blood tests
Confusion 
Anxiety 
Itching 
Heartburn  
This list includes common and less common side effects for those taking Decitabine. Side effects that are very rare -- occurring in less than about 10 percent of patients -- are not listed here. But you should always inform your health care provider if you experience any unusual symptoms.
http://www.chemocare.com/bio/decitabine.asp