The most common side effects of Tadarise Pro 40 mg are headache, flushing, and upset stomach. These side effects are usually mild and go away on their own. More serious side effects, such as priapism (a prolonged erection), can occur, but they are rare.Tadarise Pro 40 mg is not for everyone. It should not be taken by men who are allergic to tadalafil, or who have certain health conditions, such as heart disease or liver problems.