I already have a very dry scalp and seb dermatitis, would the 2 in 1 be less effective than the shampoo only?
The 1% shampoo should be just as effective against seb derm as the 2-in-1 if they have the same ketoconazole concentration. If dryness is an issue, you might try using a separate conditioner after the Nizoral. Consider using a CBD with MCT oil for extra hydration and anti-inflammatory benefits.