Ulcerative colitis take mesalazine how long to see the effect, there is no exact time, with the severity of the disease and personal constitution, in the acute attack period probably after taking the drug 3 ~ 4 days can see the effect. Ulcerative colitis can be treated with mesalazine in the acute or maintenance phase. Mesalazine is effective in 3-4 days during an acute exacerbation, and usually requires 8-12 weeks of treatment. Specific dosage and duration of treatment should be taken under the supervision of a physician, and some patients may need to take the drug for a long period of time. Mesalazine may cause dizziness, abdominal pain, hair loss, leukopenia and other adverse reactions. It is contraindicated in hepatic and renal dysfunction, hypersensitivity to the drug, bleeding tendency, and children under 2 years of age. The medication should be taken under the supervision of a physician.