Read the pattern
| What you see | Likely cause | First step |
|---|---|---|
| Temples or crown thinning over years | Male pattern hair loss | GP or clinic; medicines slow it |
| Wider parting, thin on top, over years | Female pattern hair loss | GP blood tests, then minoxidil |
| Shedding all over, started suddenly | Telogen effluvium | Wait; GP if it lasts six months |
| Round smooth bald patches | Alopecia areata | GP, who may refer you to a dermatologist |
| Thin along the hairline where hair is pulled | Traction hair loss | Loosen the style; it recovers if caught early |
| Scaly, itchy or sore patches | A scalp condition or infection | GP, soon |
| Shiny, scarred skin with no follicles | Scarring alopecia | GP, soon: early treatment saves hair |
Causes inside the body
- Low iron: the HSE lists hair loss among the symptoms of iron deficiency anaemia.
- Thyroid problems: an overactive or underactive thyroid can thin hair.
- Polycystic ovaries: hair loss on the scalp with extra hair elsewhere.
- Illness, surgery, childbirth, fast weight loss: shedding two to three months later.
- Autoimmune conditions: alopecia areata, lupus.
Medicines and treatments
Chemotherapy is the well-known one. Others can thin hair less dramatically: some blood thinners, some blood pressure and acne medicines, some antidepressants, and starting or stopping the pill. Never stop a prescribed medicine because of your hair. Ask the doctor who prescribed it.
Causes on the outside
Tight braids, ponytails and extensions pull hair out at the edges. Bleach, relaxers and heat break hair along its length. Ringworm of the scalp, mostly in children, causes scaly patches and needs tablets from a doctor. Some people pull their own hair without meaning to, a condition called trichotillomania that a GP can help with.
How hair grows, in brief
Each follicle works on its own clock. A hair grows for two to six years, rests for about three months, then falls and is replaced. At any time about one hair in ten is resting, which is why losing 50 to 100 a day is normal. Hair loss happens when follicles shrink (pattern hair loss), when too many rest at once (shedding), when they are switched off (alopecia areata), or when they are destroyed (scarring).
When to see a GP
The HSE says to see a GP if you have areas of hair loss that are itchy or sore, or hair coming out in clumps, or sudden hair loss, or if you're worried about it.
Questions people ask
What is the most common cause of hair loss?
Pattern hair loss, in both men and women. It is inherited and gets more common with age.
Can hats or washing cause hair loss?
No. Hats don't cause baldness, and washing only removes hairs that had already let go.
Which illnesses cause hair loss?
Thyroid disease, iron deficiency, polycystic ovaries, lupus and other autoimmune conditions can all do it, as can any severe illness with a fever.
Is losing 100 hairs a day normal?
Yes. Between 50 and 100 hairs a day is a normal amount to lose.