Urea 14C capsule side effects are mainly two aspects: 1, the capsule itself stimulates the gastric mucosa, causing stomach discomfort. 2, 14C has a certain degree of radioactivity, which has some harm to the human body. The first aspect, some patients can have nausea, desire to vomit and other symptoms after taking 14C urea capsules, this symptom does not require special treatment, can be appropriate to take warm water and attention, control the diet can be quickly relieved. The second aspect, 14C as a radioactive material, the human body has a certain radiation effect, especially for pregnant women, not suitable for swallowing urea 14C capsules for related examinations, in addition, adolescents are in the golden age of growth and development, also not suitable for 14C urea capsules swallowing examination.