What I said The following are some examples of how to use styling ritual that consists of intense heat and harsh chemicals on your scalp and hair—using curling and flat irons, getting frequent perms, chemical straightening procedures, or relaxing treatments—can damage the follicle and, worst-case scenario, cause permanent hair loss.
What you’ll probably notice
Hair loss is usually accompanied by changes in texture. You may notice that your hair looks frayed with tiny beads like nodes running along each strand, or feels brittle.10 “You may also notice increased breakage and shorter, uneven strands,” Dr. Mitchell says. “In more severe cases, there might be patches of thinning or an overall reduction in hair density.”
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5. Severe dandruff
There’s dandruff and then there’s its more severe cousin, seborrheic dermatitis: A pesky skin condition characterized by a rash (that may look darker, lighter, or redder than the surrounding skin), as well as itchy and flaky patches that set up shop in spots with a lot of oil glands, including your scalp. “It’s driven by an inflammatory response against organisms that live on our scalp—specifically Malassezia yeast colonies,” Dr. Lo Sicco says.11
These flaky patches, combined with the oil that’s produced by the scalp, can clog your follicles, ultimately impairing the hair’s nutrient supply and weakening its structure (not to mention the subsequent damage—and shedding—that can happen when you constantly scratch your head).12 Dr. Mitchell explains that the inflammatory reaction can disrupt the normal hair cycle and trigger telogen efluvium. This is when your hair follicles strike for a long period of time, only to shed later in large amounts.
What you’ll probably notice
Aside from the whole inflamed scalp thing, this type of hair loss isn’t usually associated with dramatic balding, but with a gradual reduction in hair density—particularly in the form of increased shedding wherever the seborrheic dermatitis is giving you the most trouble. “The hair itself may also become finer and more fragile due to the inflammatory processes disrupting the growth cycle,” Dr. Mitchell says.
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6. Inflammation of the hair follicles
Folliculitis is a skin condition that strikes when hair follicles become inflamed—say, from physical irritation (shaving, traction, wigs) or an infection (bacterial, fungal)—which compromises the integrity of the follicles.13
There are two types of folliculitis, superficial and deeper. The superficial type affects only a small part of the hair-follicle, and is likely to heal in a few weeks. However, the deep form can be severe and last for ages.
“As the follicle becomes inflamed, damage can happen to the surrounding tissues that disrupt the normal hair growth cycle,” Dr. Mitchell says. “In severe cases, the infection may lead to scarring, causing permanent hair loss.”
What you’ll probably notice
The particular type of folliculitis you experience will depend on the underlying cause (friction or infection), but “it typically presents as small acne-like bumps or pustules surrounding the affected hair follicles,” Dr. Mitchell says. “These may be itchy, tender, or painful, and in some cases form clusters that resemble a rash.” As the condition progresses, you might start noticing the surrounding skin becoming irritated and darker, lighter, or redder too.