Question: 

Dear Dr.  Nabulsi, 

Does masturbation invalidate Siyaam? Should man perform Ghusl (the full-body ritual purification, then he continues his Siyaam? Or can he continue his Siyaam with no need to perform Ghusl?

Answer: 

Dear noble brother,

Along with being forbidden, masturbation invalidates Siyaam, and one should perform Ghusl if he masturbates. Moreover, whoever masturbates on one of the days of Ramadan has committed a sin, but he should continue his Siyaam due to the sacred month of Ramadan, then he can make up this missed day after Ramadan.