I have had to use tar shampoos since my high school days. Initially I used Tegrin, but by my late twenties it no longer fully relieved the problems of itching, redness, and scaling. Not until I turned thirty and saw a dermatologist did I discover the true nature of my skin problems, almost wholly centered on the scalp and areas of facial hair--I have had a beard since my late teens. The doctor prescribed Tetracycline, with a one-month regimen, and Pentrax Coal Tar Shampoo. That did the trick, and more!
Then around 2007 Pentrax was inexplicably withdrawn, the producer giving a manufacturing issue excuse--not a credible reason after so many years on the market. I tried T-Gel, which did not even come close to controlling symptoms; Tarsum, by Summers Laboratories, rated at 2% coal tar, and it helped, but very little; then came PsoriaTrax 5% Coal Tar Shampoo, billed as the successor to Pentrax, and thought that somebody had finally "gotten it," but the symptoms remained, and even seemed to get worse.
Finally, in desperation, I tried MG217, which I had seen on the shelves of several pharmacies--primarily CVS, Rite Aid, and Walgreens (inexplicably, Duane Reade, and other regional chains do not carry it--bad purchasing practice). Even though MG217 is rated at only 3%, as opposed to the 5% of Pentrax and PsoriaTrax, it works MUCH better, fully relieving ALL symptoms, and without the usual burning sensation produced by PsoriaTrax! It is not clear to me why a product with 3% coal tar would work better than one with 5%, but I do not really care so long as it works--and IT DOES.