You will have a slight increase in side effects for a day or two with an increase in the dose, with most TCAs they settle more quickly than SSRIs but side effects at 50mg would be minimal as far as I'm aware. It's a dosage that's routinely given to the elderly and people with anorexia nervosa or those who are clinically underweight. In pill form dosulepin is manufactured in 25mg capsules and 75mg enteric coated tablets, so 25mg is the smallest possible increase in dose. Hope it works out for you!