Diagnosis Your doctor is likely to diagnose folliculitis by looking at your skin and reviewing your medical history. He or she may use a technique for microscopic examination of the skin (dermoscopy). If initial treatments don’t clear up your infection, your doctor may use a swab to take a sample of your infected skin or hair.
https://www.mayoclinic.org/diseases-conditions/folliculitis/diagnosis-treatment/drc-20361662

