Doing a colonoscopy drinking medicine and vomiting half is likely to affect the effectiveness of the bowel preparation. Colonoscopy is the most direct as well as the most effective observation of intestinal lesions in a way of examination, in the colonoscopy before the need to do a good job of intestinal preparation, generally should be based on the type of laxative to decide to take the dosage of laxatives, after taking the defecation, until the discharged excretion of the watery, no fecal slag can be. However, if in the process of taking laxatives appear nausea, vomiting symptoms lead to take the drug vomit half, it shows that the dosage of these drugs did not meet the required standard, may affect the effect of cleaning the intestinal tract, resulting in intestinal feces is not completely emptied. It is recommended to go to the hospital and consult a medical professional when you have a colonoscopy and vomit half of the medication you take. If necessary, you can change the way of cleansing the intestines or re-take the laxatives.