Wa alaykum assalamu warahmatullah,

In the Name of Allah, the All-Merciful, the Mercy-Giving

All praise is due to Allah alone; peace and blessings be upon Our Prophet Muhammad.

Apart from anal sex and sex during menses, which are utterly prohibited in Islam, other sexual practices between spouses are permissible provided that they are not detrimental to either of them.

There are some recent researches that speak about some health problems and diseases caused by oral sex. If such results are true, then oral sex becomes prohibited due to the damage and harm it causes. Otherwise, it remains permissible; though some people may find it disgusting. It is also noteworthy that it is not permissible during this oral sex to lick najasah (ritual impurities) that may be charged from sex organs.

Allah, the Exalted, knows best.