Thinning at the sides of the hair, particularly around the temples, is one of the most common patterns of hair loss in both men and women. The cause usually falls into one of a few categories: genetics, hairstyle habits, hormonal shifts, nutritional gaps, or a stress response. Figuring out which one applies to you depends on how quickly the thinning started, where exactly it’s happening, and what else is going on in your life.
Genetic Hair Loss Follows a Pattern
The most common reason for thinning at the sides is androgenetic alopecia, the hereditary form of hair loss that affects both sexes. In men, it typically starts at the temples with slight recession, eventually forming an “M” or “U” shaped hairline as the thinning deepens. In later stages, the hair between the temples and crown thins significantly or disappears entirely, leaving a band of hair around the sides and back of the head.
Women experience this differently. The frontal hairline usually stays intact, but bitemporal thinning (the area right above the ears and at the sides of the forehead) is common. A related condition called frontal fibrosing alopecia causes the hairline to recede in a band-like pattern, often affecting the temples and eyebrows. This primarily affects older women, and its cause remains unknown. Early treatment matters here because the hair loss can become permanent.
The underlying driver in genetic hair loss is a hormone called DHT, a potent byproduct of testosterone. DHT causes hair follicles in sensitive areas, particularly the temples and crown, to gradually shrink. As follicles shrink, each hair grows in thinner and shorter until eventually the follicle stops producing visible hair altogether. This process is slow, often unfolding over years, which is why many people don’t notice it until a significant amount of density is gone.
Tight Hairstyles Can Thin the Sides
If you regularly wear styles that pull at the hairline and temples, you could be dealing with traction alopecia. This is hair loss caused by repeated physical tension on the follicles, and it frequently shows up at the sides because that’s where the pull is strongest in many common styles.
The hairstyles most associated with traction alopecia include cornrows, locs, tightly braided hair, sleek ponytails, buns pulled taut, and hair extensions or weaves (especially on chemically relaxed hair). Even wearing rollers to bed regularly or pulling hair back tightly under a head covering or hat can cause enough friction and tension to damage follicles over time. People of African descent are at higher risk because the natural shape of the hair follicle makes it more vulnerable to damage from tight or rough styling.
The good news is that traction alopecia is reversible if caught early. Once you stop the pulling, the follicles can recover. But if the tension continues for months or years, the damage can become permanent as the follicles scar over and stop producing hair entirely.
Stress-Related Shedding Often Hits the Temples
Telogen effluvium is a type of temporary, widespread hair shedding triggered by a physical or emotional stressor. While it generally causes thinning across the entire scalp, it can be most prominent in the temporal areas. The characteristic timeline is a two-to-three month delay: something stresses your body (illness, surgery, major weight loss, emotional trauma, a medication change), and roughly three months later you notice clumps of hair falling out.
The shedding phase in acute telogen effluvium lasts up to six months, after which new growth starts filling in. If you can trace the thinning back to a specific event that happened a few months earlier, this is a likely explanation, and it typically resolves on its own without treatment.
Low Iron and Vitamin D Play a Role
Nutritional deficiencies are an underappreciated cause of hair thinning, particularly in women. In a study of 50 women with pattern hair loss, 40% had very low ferritin (the protein that stores iron in your body) and another 34% had levels that were low but not critically so. Only about a quarter had normal ferritin levels. The vitamin D numbers were similarly striking: 54% were deficient and 38% were insufficient, meaning over 90% of women with hair thinning had suboptimal vitamin D.
Your body needs both iron and vitamin D to maintain the hair growth cycle. When levels drop, follicles can shift prematurely into their resting phase, causing hair to thin. This is worth checking with a simple blood test, especially if your thinning doesn’t fit the typical pattern of genetic hair loss or you’ve noticed other symptoms like fatigue or muscle weakness.
How to Tell What’s Causing Your Thinning
The pattern and speed of your hair loss are the best clues. Gradual thinning concentrated at the temples over months or years points toward genetic hair loss. Thinning along the hairline in areas where you feel tension from styling suggests traction alopecia. Sudden, diffuse shedding two to three months after a stressful event looks like telogen effluvium.
A few other conditions can mimic these patterns. Alopecia areata, an autoimmune condition, occasionally presents as larger patches of loss on the temples and sides rather than the classic round bald spots. And some thyroid disorders can cause widespread thinning that may be more noticeable at the sides. A dermatologist can distinguish between these causes through a physical exam and, if needed, blood work or a closer look at the follicles.
What Actually Helps With Regrowth
The most effective approach depends on the cause. For genetic hair loss, the over-the-counter topical treatment minoxidil remains the standard first option. It works by extending the growth phase of the hair cycle and increasing blood flow to the follicles. For men, DHT-blocking medications can slow or stop the follicle-shrinking process at the temples.
If you’re looking for a less conventional option, rosemary oil has some clinical support. A six-month trial comparing rosemary oil to 2% minoxidil found that both groups saw a significant increase in hair count, with no statistical difference between them. The rosemary oil group also reported slightly less scalp itching. It’s a single small study of 50 people, so the evidence is limited, but it’s a reasonable thing to try if you prefer a plant-based approach.
For traction alopecia, the treatment is straightforward: stop wearing the hairstyle causing the tension. Switch to looser styles, avoid tight braids and ponytails, and give your hairline time to recover. For nutritional causes, correcting the underlying deficiency through diet or supplementation often restores normal hair growth over several months.
Scalp massage is sometimes recommended as a way to stimulate growth. A small study of nine men found that daily scalp massage increased individual hair thickness after six months. That’s an encouraging finding, but the evidence base is thin. It’s unlikely to hurt and may modestly help, particularly as a complement to other treatments rather than a standalone fix.