"vulgaris" Hair rash"
It means "razor burn" or "shaving burn" and can occur not only when men shave, but also when women shave their legs or arms. It is a painful bumpy condition similar to acne. Another description said that when the skin is damaged, bacteria can get in and the symptoms can worsen.
Speaking of bacteria, what I've been thinking about lately is the inside of my mouth. I'm talking about periodontal disease. Bacteria get in between the teeth and gums, causing inflammation, dissolving the bone that supports the teeth, and making the teeth loose.
According to the Ministry of Health, Labor and Welfare website, plaque contains more than 100 million bacteria per milligram, and is a different disease from tooth decay. In Japan, periodontal disease is prevalent in about 50% of people over 40 years old, and the percentage increases further for older generations. To prevent periodontal disease, brush your teeth before bed and in the morning, gently brush between each tooth and gum, and use a toothbrush at a 45-degree angle. Using interdental brushes and dental floss is also said to be effective.
This is similar to the little things you do, like using a razor or electric shaver gently to prevent shaving rash, using shaving foam or gel to protect your skin and make the razor glide smoothly, and not forgetting to use aftershave.
Some sites recommend using electric shavers in a forward shave direction and T-shaped razors in a reverse shave direction. Shave "forward" or "against" the direction of your beard growth. However, I found a razor manufacturer's website that explained that "forward shave" is recommended for those who already have razor rash. However, it also said that the direction of beard growth is not constant.
Furthermore, the opening comment about common hair follicle is a partial quote from a site that provides the furigana reading "jinjouseimousou."
https://medicalnote.jp/diseases/%E5%B0%8B%E5%B8%B8%E6%80%A7%E6%AF%9B%E7%98%A1