You’re standing in front of the bathroom mirror, clutching a bottle of expensive rosemary oil, and wondering why your hair looks exactly the same as it did four months ago. It’s frustrating. Honestly, it’s soul-crushing when you’re doing "all the right things" but the measuring tape won't budge. You start googling frantically. Why would hair stop growing suddenly, or worse, start thinning out at the temples?
Hair doesn't actually just "stop" for no reason. It isn't a broken machine. Your scalp is essentially a garden, and if the soil is bad or the weather is harsh, the plants stop reaching for the sun. Sometimes the hair is growing perfectly fine from the root, but it’s crumbling at the ends so fast that you never see the progress. Other times, your body has literally pulled the plug on your follicles to save energy for more important organs like your heart or lungs.
Biology is selfish like that.
The Anagen Phase: Your Hair’s Internal Clock
Every single hair on your head is on its own personal timeline. This is called the hair growth cycle. The big player here is the Anagen phase. This is the active growth period. For most people, this lasts anywhere from two to seven years. If your Anagen phase is naturally short, your hair might never grow past your shoulders. That’s just genetics. It’s your "terminal length."
But what if your hair used to be long and now it’s stuck?
When people ask why would hair stop growing, they’re often describing a "shortened" Anagen phase. Something has triggered your body to flick the switch from the growth phase to the Telogen (resting) phase prematurely. Instead of growing for five years, your hair decides to quit after two. When this happens on a massive scale across your scalp, it’s called Telogen Effluvium. It’s basically a synchronized strike by your hair follicles.
The Stress Connection
You’ve probably heard that stress makes your hair fall out. It’s not a myth. High levels of cortisol—the stress hormone—can actually degrade skin elements like hyaluronan and proteoglycans by over 40%. These are the "glue" that keeps your hair anchored and happy. If you had a major life upheaval, a high fever, or even a surgery three months ago, that’s likely why your growth feels non-existent right now. There is a lag time. The hair you lose today is often responding to a "shock" from ninety days ago.
Nutritional Deficiencies You’re Probably Ignoring
Your hair is made of a tough protein called keratin. To build that protein, your body needs a very specific toolkit. If you’re missing even one tool, the construction site shuts down.
Low iron is the silent killer of hair growth. Even if you aren't "anemic" by strict medical standards, having low ferritin (your iron storage) can stall your hair. Most labs say a ferritin level of 12 ng/mL is "normal," but many trichologists, like the renowned Philip Kingsley, argue that you need at least 70 ng/mL for optimal hair growth. If your storage is low, your body views hair as a luxury it can no longer afford.
- Vitamin D: It’s not just for bones. Vitamin D receptors are found in the hair follicle. If you’re inside all day, your hair pays the price.
- Zinc: This mineral helps with tissue growth and repair. A deficiency can lead to the "shunting" of the growth cycle.
- B12 and Biotin: While biotin is overhyped in gummy vitamins, a genuine B-vitamin deficiency makes it impossible for red blood cells to carry oxygen to your scalp.
Think about your diet lately. Have you been "clean eating" to the point of restriction? Rapid weight loss is one of the most common reasons why hair growth stalls. If you drop 15 pounds in a month, your follicles are going to go dormant. It’s an evolutionary survival mechanism. Your ancestors didn't need long, flowing locks to survive a famine; they needed energy for their brains.
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Hormones: The Master Controllers
Sometimes the reason why would hair stop growing is hidden deep in your endocrine system. The thyroid is a huge factor here. Whether it's hyperthyroidism or hypothyroidism, an imbalance disrupts the metabolism of the follicle itself. The hair becomes brittle, dry, and refuses to lengthen.
Then there’s DHT. Dihydrotestosterone.
In Androgenetic Alopecia (male or female pattern baldness), follicles are sensitive to DHT. This hormone causes the follicle to shrink, a process called miniaturization. Each time a hair falls out and regrows, it comes back thinner, shorter, and weaker. Eventually, the follicle becomes so small it produces only "peach fuzz," or stops producing hair entirely. This isn't just a "guy thing." Women going through menopause or those with PCOS (Polycystic Ovary Syndrome) often see their hair growth stall because their estrogen levels drop and androgens take the lead.
Is It Growth or Is It Breakage?
Here is a hard truth: your hair might be growing perfectly fine at the root, but you’re "losing" it at the bottom. This is the "false plateau."
If you use a flat iron every day at 450 degrees, you are literally cooking the protein. The cuticle—the protective outer layer—shatters. Once that happens, the inner core of the hair leaks moisture and snaps. If your hair grows half an inch a month, but you break off half an inch of split ends every month, your length will never change.
You can check this yourself. Look at a strand of hair that has fallen out. Does it have a tiny white bulb at the end? If yes, it fell out from the root. If there’s no bulb and the end looks frayed or blunt, it’s breakage. Mechanical damage from tight ponytails (traction alopecia) or chemical damage from over-bleaching are the most common culprits.
Scalp Health: The Forgotten Factor
We spend hundreds of dollars on serums for the hair shaft, which is technically dead tissue. We ignore the scalp, which is the only living part. Inflammation is the enemy of growth.
Conditions like seborrheic dermatitis (basically intense dandruff) or scalp psoriasis create a hostile environment. Fungal overgrowth or excessive oil can clog the pore. While "clogged pores" causing baldness is a bit of an old wives' tale, chronic inflammation around the follicle definitely inhibits the Anagen phase. A healthy scalp should feel loose and move easily over the skull. If it’s tight and inflamed, blood flow is restricted.
Specific Steps to Restart Your Growth
If you feel like your hair has hit a wall, don't just buy a random supplement. You need a targeted plan.
First, get bloodwork done. Specifically, ask for a full iron panel, Ferritin, Vitamin D, B12, and a Thyroid-Stimulating Hormone (TSH) test. Don't just settle for "you're in the normal range." Ask for the actual numbers. If your ferritin is under 50, talk to a doctor about an iron-rich diet or supplementation.
Second, audit your protein intake. Most people, especially women, vastly underestimate how much protein they need for hair health. Aim for at least 0.8 to 1 gram of protein per kilogram of body weight. If you aren't eating enough amino acids, your body cannot synthesize keratin. Period.
Third, stimulate blood flow. Scalp massages actually work, but not because of "magic." They physically stretch the cells of the hair follicles, which stimulates them to produce thicker hair. In a 2016 study, participants who did 4 minutes of scalp massage a day for several weeks saw increased hair thickness. It's free. Do it while you're watching TV.
Fourth, check your products. Stop using heavy silicones that mask damage and start using products that support the scalp microbiome. If you have been avoiding washing your hair to "save" it, you might be doing the opposite. For most, washing every 2-3 days keeps the scalp clear of DHT-laden sebum and inflammatory oils.
Finally, manage the ends. If you're dealing with breakage, you need a bond-builder like Olaplex or K18. These aren't just conditioners; they actually work on a molecular level to relink the broken disulfide bonds in your hair. And yes, you might need a "dusting" (a very tiny trim) to stop split ends from traveling up the hair shaft like a run in a stocking.
Understanding the Timeline
Patience is the hardest part of this. Hair grows, on average, about six inches per year. If you make a change today—like fixing a vitamin deficiency or reducing stress—you won't see the results in the mirror tomorrow. It takes about three to six months for the "new" growth to be visible at the scalp. You have to play the long game.
Avoid the "miracle" TikTok trends. Rice water can help with protein, but it can also make hair brittle if overused. Rosemary oil has some evidence suggesting it’s as effective as 2% Minoxidil, but it requires consistent, daily application for months. There are no shortcuts. Your hair is a reflection of your internal health. If your growth has stopped, it’s a signal from your body. Listen to it.
Start by addressing the internal triggers. Fix the "soil" of your scalp. Protect the length you already have. If you do those three things, the growth will return.
Actionable Next Steps:
- Track your shed: Count the hairs in your brush for three days. Losing 50-100 is normal; 200+ suggests Telogen Effluvium.
- Ferritin Check: Book a blood test to ensure your iron storage is above 70 ng/mL.
- Protein Audit: Track your food for 48 hours to see if you’re actually hitting 60g+ of protein daily.
- The Bulb Test: Examine five fallen hairs to distinguish between root loss and mechanical breakage.