What is semen?
Semen is mostly water. Semen also contains amino acids and protein, sugars such as fructose and glucose, minerals such as zinc and calcium, vitamin C, and a few other nutrients.Sperm cells themselves make up less than one percent of semen* and are not present for men who have had a vasectomy. Semen is edible, and if swallowed, will travel down the esophagus and into the stomach, where it will be digested in the same way that food is.
Because of these above reasons some studies claims that their is nothing wrong in swallowing semen,but others studies claims it to be bad for health.
In rare cases, a person may discover that they have an allergy to the proteins found in semen: a condition known as seminal plasma hypersensitivity.
Before you engage in fellatio,you and your partner both should get tested for sexually transmitted infections (STIs) or (STDs).If you do have these infections or disease then it is extremely dangerous for your health and will ultimately ruin your whole life.So its up to you to do it or not.