Start with a veterinary examination to ensure there is no concurrent health problem or skin condition (infection or mange) to exacerbate the shedding.
If okay, he may have an intense undercoat that requires regular grooming. Sometimes, essential fatty acid supplements can be helpful.
I prefer the veterinary products, which are already dosed for pets. Your vet
should carry a product on their shelf, or over-the-internet you can look for Aller G3, 3V caps, EFA-z, or Derm caps.
My only concern is that a vet needs to evaluate the skin to ensure there is not a primary cause for the excess shedding.