Now, I am not totally anti-co-washing, in fact, I think if you want to wash your hair more than once a week it is far better to co-wash between weekly shampoos.
A few people I know have found that after co-washing only their hair gets drier and more brittle and they think that it's the co-washing that is to blame.
The answer is: NO. Co-washing does not make your hair more dry in itself but it is EXTREMELY restrictive in what products you can use.
Some ingredients in conditioners and leave-in moisturizers stick to your when applied so that they can keep your hair conditioned and moisturized for a while after the conditioning or moisturizing session.
Some of these ingredients, will not wash off without shampoo. So when you re-apply your products these ingredients continue to build up and build up until your hair is indeed brittle, dry and starts breaking.
Most co-washers are not educated enough about ingredients to know what they need to avoid. In fact, although I know a fair amount of what's a no-no for co-washers I would need to take a list when I go shopping because I wouldn't remember everything off by heart. Importantly, no list is exhaustive. This means no list will list everything and no list can because new ingredients are coming out all the time.
So, what should co-washers avoid, in general:
- Non-soluble Silicones (water-soluble ones are completely fine)
- Mineral oils
- Go for oils high in saturated fats and monounsaturated fats as listed in THE Best Oil For Natural Hair. A Mega Summary! because these will penetrate into hair whereas other oils mostly sit on the hair cuticle. The best oil is Jojoba, second best is coconut oil, third best is avocado oil.
In summary, co-washing can work if you make an effort to learn everything that must be avoided, however, in my opinion a co-wash only regimen is not worth it because shampoo does have an important role to play in healthy hair management: A clean, pliable and healthy scalp is essential for natural hair growth and clean hair is need to moisturise and condition hair effectively.