Pros: helps dry itchy scalp, especially when caused by eczema
Cons: expensive, leaves hair brittle and not as soft, smell clashes with other products
I have eczema, and over the past few years one of the areas most affected has been my scalp. The frigid temperatures of recent winters have exacerbated this problem, resulting in a lot more itchiness than normal. Both my dermatologist and my hairdresser independently recommended Paul Mitchell Tea Tree shampoo.
I've been using it for about 18 months now. At first I didn't find it much help. I had been lathering through all of my hair then rinsing immediately. Then one time I accidentally left it sitting in my hair slightly longer and I felt my head start to tingle. Taking this as a good sign, I didn't rinse right away. That was the first time I noticed a difference after using the shampoo. Now I always wash my hair twice - once quickly with an immediate rinse and a second time more slowly and thoroughly. On this second pass, I allow the shampoo to sit in my hair as I take the rest of my shower, then I rinse it off when I finish. By that time, my scalp has been tingling for several minutes and has gotten a lengthy application of the tea tree oil.
Used this way, the shampoo definitely helps my eczema, although in the dead of winter some itchiness can reappear within a few hours of application. In fairness, these past two winters have been very very harsh, with sub-zero temperatures (in Fahrenheit) and strong winds for extended periods of time. My eczema has been much worse than usual since the severest portions of last winter so the shampoo has had much to overcome.
While it does work on my scalp, I find the shampoo less than effective on my hair. My hair tends to get very soft just after washed when I use other products. While it's definitely still softer after being washed, it doesn't get nearly as soft with these products. Also, since I've started using them, my hair has been much more brittle and prone to falling out more when brushed. Fortunately I have very thick hair so this just serves to thin it out a bit. The graying process has also accelerated significantly. These symptoms are all a fairly normal part of the aging process so it's possible that their onset just happened to coincide with the change of shampoo and conditioner, but at 32 I am hardly decrepit and it seems unlikely to me that these problems would have all started at exactly the same time at a relatively young age without some sort of external stimulus. Since they started soon after I started using Paul Mitchell Tea Tree shampoo and conditioner, I can only speculate that the two are related.
Tea tree oil has a very strong astringent smell, so this shampoo needs a very strong scent to somewhat mask the oil. They went with mint. While I like mint and don't have a major problem with the smell, I find I miss the softer fruit and flower scents of other shampoos I've used in the past. The good news is that the mint scent dissipates very quickly so you're not walking around in a mint haze for any length of time. Of course, this also means that you can't use the shampoo in lieu of more expensive perfume as I've done in the past with other shampoos with scents that linger.
Paul Mitchell Tea Tree shampoo is horribly expensive at $8 for an 8 ounce bottle and $15 for a 16 ounce bottle (at the moment; they've changed the bottles and sizes twice already in the 18 months since I've been using the product). I've spent more on shampoo in the past 18 months than the ten years previous. To be honest, I find that a $1 bottle of Suave shampoo does a much better job on my hair itself. However, the Paul Mitchell Tea Tree shampoo works wonders for my dry scalp caused by eczema. Because of this, although I am not entirely thrilled with the shampoo, I continue to use it.