All medications may cause side effects, but usually patients have no, or minor, side effects. Common side effects may include: Nausea or vomiting, Abdominal pain, Diarrhea, Hair loss, Weakness, Nerve irritation One of the most worrisome side effects of Colcrys is that it can damage the bone marrow causing severe anemia, low white blood counts, and low platelets. Reduced white blood cell counts may increase the risk of infections. All patients taking Colcrys long-term require monitoring of their blood counts. Colcrys also may causemuscle pain (myopathy)or severe muscle breakdown. To reduce your risk for serious side effects, do not increase your dose, take it more frequently, or take it for a longer time than directed by your doctor. Serious side effects may occur even at usual prescribed doses. The above noted side effects may not require medical attention and may slowly decrease over time as your body adjusts to the medication. Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.