I am suffering from dermatitis after shaving beard. what should i do?

Dermatitis: Use over the counter or prescribed corticosteroid creams or ointments or oral tablets or injections, antibiotics- you may need antibiotics if you have a bacterial skin infection or an open sore or fissure caused by scratching, oral antihistamines, immunomodulators, and light therapy. Hope this helped :].

Shaving dermatitis: Razor dermatitis is a very common problem seen in men. Causes are myriad, but to do this you must see a dermatologist. If this is a condition called pseudofolliculitis barbae, laser treatments are the only thing i've ever seen works excellently in this condition. Often antibiotics are used along with agents to firm up the sirface of the skin. But you need to see a dermatologist.