By: Robin Lewallen, MD, FAAD
Noticing more hair in your shower, on your pillow, or in your brush can be alarming. While it’s normal to lose 50–100 hairs each day, sudden or excessive shedding may signal an underlying problem.
The good news? Many causes of hair loss are treatable once the correct diagnosis is made.
1. Telogen Effluvium
The most common cause of sudden hair loss is telogen effluvium, a condition where more hairs than usual enter the resting phase of the hair cycle and shed several months later.
- Common triggers include:
- Significant illness or high fever
- Surgery or hospitalization
- Childbirth
- Emotional stress
- Rapid weight loss or restrictive dieting
- GLP-1 weight loss medications
- Iron deficiency or poor nutrition
- Thyroid disorders
- Starting or stopping certain medications
Because shedding often begins 2–3 months after the trigger, many people don’t realize the two events are connected.
2. Male or Female Pattern Hair Loss
Sometimes hair loss isn’t truly sudden. Many men and women have gradual thinning that becomes much more noticeable after an episode of increased shedding.
Signs include:
- A widening part
- Decreased hair volume
- A smaller ponytail
- Increased visibility of the scalp near the crown or temples
3. Alopecia Areata
If you’re developing smooth, round bald patches instead of shedding evenly across the scalp, an autoimmune condition called alopecia areata may be the cause. Early treatment can improve the chances of regrowth.
4. Scalp Conditions
Inflammation of the scalp can also contribute to hair loss. Conditions such as dandruff, psoriasis, allergic reactions, or certain inflammatory disorders such as lupus, lichen planopilaris, frontal fibrosing alopecia, or central centrifugal cicatricial alopecia may cause itching, burning, redness, scaling, and hair thinning. Some inflammatory conditions can lead to permanent hair loss if not treated promptly.
5. Hair Breakage
Not all “hair loss” comes from the root. Frequent heat styling, bleaching, tight hairstyles, or chemical treatments can cause hair shafts to break, making the hair appear thinner even though the follicles remain healthy.
When Should You See a Dermatologist?
Schedule an evaluation if:
- Shedding continues for more than 6–8 weeks
- Your hair is becoming visibly thinner
- You develop bald patches
- Your scalp is itchy, painful, or inflamed
- Your part is widening or your ponytail feels smaller
A dermatologist can often identify the cause through a scalp examination and, when appropriate, may recommend blood work or other testing to guide treatment.
The Bottom Line
Sudden hair loss is common, but it isn’t something you should ignore. Whether the cause is temporary shedding, pattern hair loss, an inflammatory scalp condition, or hair breakage, identifying the underlying reason is the first step toward effective treatment and, in many cases, healthy regrowth.
