Did I develop an allergic reaction? (Photo)

Without examining the area, determining the exact cause of the redness on the face is impossible. If you suspect that this is due to the minoxidil, then the best recommendation is to stop using it and see how the face reacts. If it persists, I recommend seeing a dermatologist for evaluation.

İf the redness happens right after you apply minoxidil than it can be considered an allergy for Minoxidil's active ingredient.

You could have an allergy induced by the dermaroller or just using the minoxidil some people do develop allergies