If your hair has started to feel different — drier, coarser, wiry, brittle, or simply not the way it used to — it is easy to put it down to a new product, hard water, or the weather. But when the change is persistent and nothing external explains it, the cause is often internal.
A change in hair texture is one of the more commonly overlooked signs that something is happening within the body. At Fibre Trichology in Congleton, Cheshire, Mandy regularly sees clients whose hair texture has shifted — sometimes suddenly, sometimes gradually — and in many cases an underlying medical condition or health change is a significant contributing factor.
Here is a breakdown of the most common medical causes of hair texture change, and what steps are worth taking if you are concerned.
Hair texture changes can present in a number of ways. Some of the most common descriptions from clients include:
Any of these changes — particularly when they come on suddenly or worsen progressively — are worth investigating, especially when they coincide with other symptoms such as fatigue, weight changes, mood shifts or increased hair loss.
Thyroid dysfunction is one of the most well-established medical causes of hair texture change and one of the first things a trichologist will consider when a client presents with unexplained changes to their hair.
An underactive thyroid (hypothyroidism) slows the body’s metabolic processes — and the hair follicles are among the first structures to be affected. Hair often becomes dry, coarse, brittle and dull, may shed more than usual, and can grow more slowly than before. In some cases the outer third of the eyebrows thins as well — a detail that can help point towards a thyroid cause.
An overactive thyroid (hyperthyroidism) tends to produce finer, softer hair that sheds excessively and loses its body and volume. The scalp may feel more sensitive than usual.
Because thyroid symptoms develop gradually and overlap with many other conditions, thyroid-related hair changes are frequently attributed to other causes for some time before the underlying problem is identified. A full thyroid blood panel — including TSH, Free T3 and Free T4 — is the most reliable way to assess whether thyroid function is a factor. Our guide to blood tests for hair loss explains which tests are most relevant and why the full panel matters.
Low iron — and specifically low ferritin, the protein that stores iron in the body — is one of the most common nutritional causes of both hair loss and a noticeable change in hair texture. When ferritin levels drop, the body redirects iron away from non-essential structures like the hair follicle in order to protect vital organs. The result is often hair that grows back finer, weaker and more prone to breakage than before.
Hair affected by low ferritin can feel limp, dry and lacking in its usual resilience. It may snap more easily when brushed or styled and may appear dull rather than shiny. Iron deficiency is particularly common in women — especially those with heavy periods, those who have recently given birth, or those following a plant-based diet.
Standard iron blood tests can sometimes appear within the normal range even when ferritin is low enough to affect hair health, which is why it is important for the right tests to be requested and interpreted alongside the clinical picture.
PCOS is a hormonal condition that affects androgen levels in women. Elevated androgens can cause hair follicles on the scalp to miniaturise over time, producing finer and shorter hairs — a process similar to androgenetic alopecia. At the same time, androgen excess can cause changes in scalp oiliness, which affects how the hair feels and behaves overall.
Women with PCOS may notice scalp hair becoming finer and less dense while experiencing increased facial or body hair. The hair changes associated with PCOS tend to be gradual, which is why they are sometimes only noticed after a period of increased shedding draws attention to a shift in density and texture that had been developing for some time.
The hormonal changes that accompany perimenopause and menopause — particularly falling oestrogen levels — can have a significant effect on hair quality. Oestrogen helps to keep hair in its active growth phase for longer and supports the overall health of the follicle. As levels decline, hair can become finer, drier and more fragile, with a reduced growth rate and a tendency to break more easily.
