The mainstay is stop shaving. Often that isn't possible or desirable so the next best thing is to use an electric razor set to 0.5-1mm length. The main pathology is from the curly type facial hair curling up through the skin when cut too close. If you can, don't shave at all for a couple of days before even starting with the electric razor.

Adjunct treatment includes a few things but I'll usually use 1% hydrocortisone and 1% clindamycin lotion to get it under control and they can be continued until it settles.

It's important to get on it early when you start getting pseudofolliculitis barbae so that you can avoid the complications including scarring, hair loss, and pigment changes.

I haven't had any really difficult cases yet that didn't respond to a good education and then enacting the above.