Is it permissible to swallow semen after having oral sex?

Swallowing semen necessitates consulting a specialized physician to know the degree of harm it may result from this. According to Islamic law, if it is proved that swallowing semen is not harmful, it becomes then undesirable because it is deemed filthy. According to the opinion of some scholars, it is deemed ritually impure [najis).

However, if it is proved that swallowing semen is harmful, it is prohibited [haram] based on the legal axiom which says, "Harm must be removed".