The invention relates to the therapy of diseases associated with the activity of histamine receptors, in particular for the treatment of allergic diseases, preferably the therapy of perennial and persistent allergic rhinitis, itch, as well as a number of other diseases associated with the activity of histamine receptor type 3 and/or 4, using compound N,N′-bis(2-(1H-imidazol-5-yl)ethyl)malonamide. This compound, as well as pharmaceutically acceptable salts, hydrates, or solvates thereof, is an antagonist of histamine receptor type 3 and/or 4. The invention also relates to pharmaceutical compositions containing a therapeutically effective amount of Compound I.