The strength of the stuff in Yohimbe that works for erectile dysfunction is not regulated. Too, bad, too. Because it really does work. But it does not work the same way as Cialis or Viagra do. It also does not work for everyone. A couple of friends have had allergic reactions to the tincture. I used to add a couple of drops of the tincture available at GNC in my rave shake; a concoction that I'd whip up in the blender and suck down before going out clubbing. Never had any problem with the stuff. However, because it is has not been established what strength or how much works I would only recommend it if you're under 40 and have no history of heart disease or hypertension in you or your family. Too much of the stuff and you can end up feeling suddenly compelled to clean the house top to bottom two or three times in a row. Use with caution.