Here is a previous post that I cut and pasted in for you. It's long winded, but I hope it helps you:
For the US folks here, T/Gel with Salycilic Acid is marketed domestically as 'T/Sal'. You can find in at the grocery store. As for the other various types of T-Gel, here is the lowdown on what they all are:
Theraputic ('Normal') T-Gel contains .5% Coal Tar, the active ingredient. Coal Tar is an antifungal. Then there is T-Gel Intensive Anti-Flake which contains, I believe, 1% Coal Tar. Same strategy, more chemical. There is also another variety of T-Gel the specific name I forget but it is something to the effect of 'anti-itch'. It contains .5% Coal Tar, and also contains Menthol which is a mild topical anesthetic and feels good on the scalp. Then, there is T-Sal, which does not have Coal Tar, but has Salycilic Acid as its active ingredient. T-Sal also comes in normal and enhanced strength.
Coal Tar is an antifungal, which helps keep in check naturally occurring fungi on the scalp that can cause itching and flaking. This is IMPORTANT because the itching and flaking from the fungi act synergistically with the natural immune response occurring in male pattern baldness-affected follicles to accelerate the male pattern baldness process.
Salycilic Acid is an exfoliant, a 'fruit acid', that helps break down dead scalp tissue and makes it much more easier for the soap ingredient in the shampoo to wash away. Both are two methods of attack against the same basic problem. I would start with T-Gel Theraputic and see how it works, then you can meander to any of the other products depending on the results you get from it.
Nizoral contains Ketoanalconahole, which is also an antifungal that attacks the irritation cycle in the same fashion as Coal Tar. However, Ketoanalconahole has also been found to contain some anti-androgenetic properties that facilitate hair maintenance over and above the anti-fungal properties. In this fashion, one would think that Nizoral would be better, but I have heard it suggested that even a regular Nizoral user should rotate a little T-Gel in to keep those fungi buggers off balance and to not let them get accostumed to one form of barrage. T-Sal is NOT an antifungal, but as the antifungals do, it does help with flaking, and has the added benefit of, anecdotally speaking, improving the absorbtion of topicals by clearing the scalp of excess dead skin.
There you have it. I say find what works for you, pick and choose, mix and match, and concoct the ultimate chemical soup that keeps your scalp happy
