Chronic telogen effluvium (CTE) is a prolonged form of hair shedding that lasts six months or longer, sometimes persisting for years. Unlike the more common acute version, which resolves on its own within a few months, CTE involves ongoing, diffuse hair loss across the entire scalp without a clear single trigger. It is the most common cause of non-scarring, diffuse hair loss in women, and the vast majority of people diagnosed are women between the ages of 18 and 45.
How Normal Hair Cycling Goes Wrong
Your hair grows in cycles. Each follicle spends several years in an active growth phase, then transitions into a brief resting phase lasting two to three months before the hair falls out and a new one begins growing. At any given time, roughly 5 to 10 percent of your scalp hair is in this resting phase.
In telogen effluvium, something pushes a much larger percentage of follicles into the resting phase at once. When those hairs reach the end of their resting period two to three months later, they all shed together. That delay is why people often notice heavy shedding months after the event that caused it. In the acute form, the trigger is usually a single identifiable event, and hair returns to normal once new growth catches up. In CTE, the shedding cycle keeps repeating without a clear resolution point.
What Triggers It
Acute telogen effluvium has a recognizable list of triggers: high fever, childbirth, severe infection, major surgery, crash dieting, sudden hormonal shifts (like stopping birth control), and certain medications including beta-blockers, retinoids, and anticoagulants. Iron deficiency, low protein intake, and thyroid dysfunction are also well-established causes. Postpartum shedding, for example, typically begins two to four months after delivery, lasts about two months, and resolves with full recovery.
Chronic telogen effluvium is more complicated. Sometimes it begins with one of these same triggers but simply never resolves. Other times, multiple low-grade stressors overlap: mild iron depletion combined with ongoing psychological stress and a borderline thyroid issue, none severe enough on their own to cause dramatic shedding but together enough to keep follicles cycling abnormally. In many CTE cases, no clear cause is ever identified, which is one of the most frustrating aspects for patients.
Who It Affects
CTE overwhelmingly affects women. In a large single-center review of 2,851 female patients with telogen effluvium, 83.5 percent were between 18 and 45 years old, with a mean age of about 26. Only 3.7 percent were over 45, and about 13 percent were under 18. While men can develop telogen effluvium, they are far less frequently diagnosed with the chronic form, partly because male-pattern hair loss is so common that it often masks or is confused with diffuse shedding.
What It Looks and Feels Like
CTE does not cause bald patches. Instead, you notice diffuse thinning spread evenly across the scalp. Hair feels thinner overall, ponytails lose volume, and you find significantly more hair on your pillow, in the shower drain, and on your brush than you used to. Some people describe being able to run their fingers through their hair and coming away with several strands each time.
The shedding often fluctuates. You may have weeks where it seems to slow down, followed by waves of heavier loss. This waxing and waning pattern is characteristic of CTE and can make it hard to tell whether things are improving. Importantly, the scalp itself typically looks normal, with no redness, scarring, or flaking. The hair that does grow back comes in at normal thickness, which distinguishes CTE from female-pattern hair loss, where individual strands progressively miniaturize and become finer over time.
How It’s Diagnosed
There is no single definitive test for CTE. Diagnosis is primarily clinical, based on the pattern of shedding, its duration, and ruling out other causes. One common in-office assessment is the hair pull test: a doctor grasps 20 to 60 hairs between their fingers near the scalp and tugs firmly but gently. If more than 10 percent of those hairs come out, the test is considered positive and suggests active shedding.
Blood work is typically ordered to screen for treatable underlying causes. The standard panel usually includes iron studies, thyroid function tests, and sometimes vitamin B12 and vitamin D levels. Interestingly, at least one study comparing 90 women with CTE to 90 controls found no significant differences in hemoglobin, ferritin, vitamin B12, vitamin D, copper, biotin, or thyroid function between the two groups. This underscores a frustrating reality: for many women with CTE, blood work comes back entirely normal.
That said, ferritin deserves special attention. Some research points to a critical threshold of 40 ng/mL, below which increased telogen shedding is more likely. Many women have ferritin levels that fall within the “normal” lab range (often as low as 12 ng/mL) but still below this hair-specific threshold. If your ferritin is under 40, addressing it through diet or supplementation may help even if your doctor says your levels are technically fine.
How CTE Differs From Female-Pattern Hair Loss
These two conditions overlap enough that they can coexist in the same person, making diagnosis tricky. The key differences come down to pattern and hair quality. Female-pattern hair loss tends to thin most visibly along the center part and crown of the scalp, and the individual hairs that grow back are progressively finer and shorter. CTE causes diffuse shedding across the entire scalp, including the sides and back, and regrown hairs come in at their normal diameter.
Another practical difference: if you gather a handful of shed hairs and look at the roots, CTE hairs will have a small white bulb at the base (indicating they completed the resting phase normally). In female-pattern loss, hairs may break or shed at various stages. A dermatologist can also use a magnifying tool called a dermoscope to look for miniaturized hairs, which point toward pattern loss rather than CTE.
Treatment and Management
When a specific trigger is identified, treating it is the first step. Correcting iron deficiency, optimizing thyroid levels, adjusting a medication, or managing chronic stress can sometimes slow or stop the shedding. The challenge with CTE is that improvement takes time. You should not expect visible changes in less than three months of treatment, and full recovery can take six to twelve months because hair grows slowly, roughly half an inch per month.
For cases where no correctable cause is found, or where shedding persists despite addressing known triggers, low-dose oral minoxidil has shown promise. In a study of 36 women with CTE who took daily doses ranging from 0.25 to 2.5 mg (most commonly 1 mg), significant improvement in shedding was seen in 31 of the 36 participants over six months, with continued gains at twelve months. This is a much lower dose than what is used for blood pressure (its original purpose), which means side effects are generally mild.
Topical minoxidil, the over-the-counter version applied directly to the scalp, is another option, though some women find it difficult to use consistently and dislike the texture or scalp irritation it can cause. Both forms work by extending the growth phase of the hair cycle and increasing blood flow to the follicle.
What to Realistically Expect
CTE rarely causes total baldness. Most women retain enough hair density that the thinning is noticeable primarily to themselves, though it can be distressing. The condition tends to follow a fluctuating course over months or years, with periods of heavier shedding alternating with relative calm.
Many women with CTE do eventually see improvement, but the timeline is unpredictable. Monitoring your shedding once a month, rather than daily, gives a more accurate picture of whether things are trending in the right direction. One practical approach is a modified wash test: collecting and counting the hairs lost during a standardized wash on the same day each month. This removes the emotional noise of day-to-day variability and gives you something concrete to track over time.
Nutritional optimization also matters even when blood work looks normal. Ensuring adequate protein intake (hair is made almost entirely of protein), maintaining ferritin above 40 ng/mL, and managing stress are baseline strategies that support healthy hair cycling regardless of whether a specific deficiency has been identified.