A coconut oil shampoo may be better than others made with other oils. But if I were you, I would stick with just pure coconut oil.
I have tried several shampoos with coconut oil as their "alleged" predominant ingredient. But they all failed to address my dandruff concern. I can think of one reason for this failure. The manufacturers must have put harmful ingredients in them.
It's only when I used pure coconut oil that I was able to solve my dandruff and hair loss dilemma. Note that the coconut oil, itself, is not the shampoo. This is how I do it...
I massage a liberal amount, about 1-2 tablespoons on my hair and deep into my scalp. I have short hair so adjust accordingly.
Make sure the oil stays on for around 30 minutes, preferably up to an hour if you have the time. Use a shower cap if you have to. Overnight is best!
Then wash it out with the mildest shampoo you can get your hands on. You can add a touch of oil after washing. A few drops won't make your hair look oily but is enough to give it a little extra shine.
I do this regimen 2-3 times a week but with a twist. I do it after taking a bath. Experiment with your own unique situation for best results.
Of course, if you can find a "truly" all-natural coconut oil shampoo, then by all means, use that! That works for me, too. You can use that or pure coconut oil in combination with the gentlest shampoo you can find.
Coconut oil contains a rich amount of Medium Chain Triglycerides (MCT). The same MCTs found in sebum, the oily substance sebaceous glands secrete to lubricate your hair and keep your scalp from drying and breaking.
MCTs transform into Medium Chain Fatty Acids (MCFA), the "antimicrobial powerhouse" that gives coconut oil its amazing ability to vanquish bacteria, viruses and other microbes, including the fungi that cause dandruff.