Prokarin

Prokarin (also known as Procarin) is an alternative medicine that consists of a mixture of histamine and caffeine. It is marketed as a treatment for fatigue in multiple sclerosis (MS),[1] although in the 1950s multiple sclerosis was believed to be an alergic condition and Prokarin was developed as a treatment for the condition.[2] The idea behind this combination is that caffeine is a generally well tolerated stimulant which can help treat fatigue. Like most stimulants, caffeine causes vasoconstriction, so the vasodilation effects from concomitant histamine can counteract this. Prokarin is formulated as a transdermal patch since histamine isn't well absorbed when consumed orally. While brand name Prokarin can be expensive, it can be compounded by pharmacists if prescribed by a physician.[3]

Quackwatch lists Prokarin as one of the multiple sclerosis "cures" of which people should be wary.[3] While it doesn't treat the disease progression of MS, its usage for symptomatic management of fatigue in MS is controversial.