Mens Defectii is a magicalpotion which sole purpose is to reduce many of the Flux Blight disease's symptoms. It is considered to be one of the most difficult potions to manufacture, not mentioning the severe side effects the potions has if drank by someone not suffering from Flux Blight.
Even if drank by a sufferer of Flux Blight, it is highly recommended that one should use it sparingly, as it can cause slurred speech and slow, uncertain reflexes if drank more than prescribed by a healer. Usually, someone suffering from Flux Blight has to drink the potion three times a day; once at breakfast, then at lunch, and finally at dinner. If drank too much, the toxicity of the potion will increase. If drank too few, the potion will be ineffective.