Is it permissible to use creams that contain alcohol, such as Jergens cream, and how can one determine if the alcohol has transformed into another substance, and is it necessary to abstain from using all creams and perfumes and suffice with musk and oud oil?

The ruling on creams and perfumes depends on their constituent ingredients. If they are pure, they are permissible unless their use leads to harm. If they are compounded from impure substances, such as alcohol and the like, then the ruling is prohibition, unless they undergo a complete transformation (istihalah). This is the view of Shaykh al-Islam Ibn Taymiyyah and Ibn al-Qayyim. Istihalah means the transformation of a substance into another substance that differs from it in definition and reality, thus becoming pure. So, if an impure substance (alcohol) transforms into another substance and its characteristics are eliminated, then it becomes pure and its use in creams is permissible. However, if it is added before the transformation, then the creams become impure and their use is not allowed. If there is doubt about its transformation, the default is that transformation has not occurred, and the impurity remains. The reference for determining transformation is the specialists in the field. It is not obligatory to abstain from all perfumes and creams. However, if it is highly probable that a certain type contains alcohol, then it is obligatory to abandon it; otherwise, there is no harm in using it, because the default rule for things is permissibility.