My brother is suffering from the sickness of doubt... So, is there a cure for this sickness?

A patient suffering from Obsessive-Compulsive Disorder (OCD) is advised to pursue two paths of treatment:

1. Religious Treatment: This begins by refraining from indulging in doubt, as the jurists have stipulated that a person afflicted with waswas (obsessive whispers) should not pay attention to his doubts. It was also reported from Ibn al-Qayyim that overcoming waswas is achieved by following the Sunnah of the Messenger of Allah, peace be upon him, and by being convinced that Satan is an enemy who invites to the Blazing Fire. One must also diligently observe the prescribed adhkar (remembrances) and awrad (litany) with reflection and contemplation, read the Quran, especially Surah Al-Baqarah, and persist in supplication.

2. Behavioral Therapy: This requires consulting a specialized physician or psychological counselor who can provide appropriate methods of treatment and may prescribe beneficial medications, in order to address the complications of waswas before it is too late.