DR KAYE: Why everything you think you know about dandruff is wrong

What can I do about my itchy, flaky scalp?

Dr Philippa Kaye answers: The most likely cause of an itchy, flaky scalp is dandruff – an unpleasant but easily treated skin condition.

Many patients wrongly assume these white flakes – which can shed onto clothes – are dry skin. However, the condition is linked to a yeast called malassezia, which lives naturally on the scalp.

Almost all adults carry this yeast – it’s not something that can be caught or avoided.

In fact, malassezia is good for the body as it helps break down the natural oil – sebum – that accumulates on the scalp. This process produces something called oleic acid.

But, for around half the population, oleic acid can irritate the scalp, triggering inflammation. In turn, this causes the body to overproduce skin cells, which leads to the tell-tale dandruff skin flakes, as well as itching.

Many patients mistakenly believe dandruff is caused by poor hygiene and, as such, assume that regularly washing the hair can help cure the problem.

However, this only temporarily removes visible flakes – but does not treat the underlying issue.

Instead, the most effective treatments are medicated anti-dandruff shampoos.

Shampoos containing pyrithione zinc — such as Head & Shoulders, typically priced between £3 and £6 — work by reducing the levels of malassezia on the scalp and can be used regularly.

Some patients also benefit from shampoos that contain tar, such as Polytar (usually around £12), which slows down the production of new skin cells, reducing severe flaking. 

However, shampoos containing coal tar often have a strong smell and may temporarily stain or discolour lighter hair.

For more stubborn cases, ketoconazole shampoos such as Nizoral (around £6 to £10) act as antifungals, actively killing the yeast.

These should be used twice weekly for two to four weeks, and left on the scalp for around five minutes before rinsing to ensure they are effective. Once symptoms improve, patients should use the shampoo once a week to prevent recurrence.

It is important that patients use these treatments consistently and allow time for them to work. Switching products too quickly is a common reason for poor results.

Alongside treatment, patients should regularly wash their hair. Although dandruff is often mistaken for a dry scalp, it is usually associated with increased oil production. Allowing oil to build up can worsen the condition, as the yeast thrives in this environment.

For this reason, applying oils to the scalp — such as coconut oil — is not recommended. While these products are often promoted online as natural remedies, they can exacerbate dandruff by providing more of the oil that the yeast feeds on.

However, there are some natural remedies that may help combat dandruff.

Shampoos containing tea tree oil (typically £5 to £10) have mild antifungal properties and may offer some benefit, although they are generally less effective than medicated treatments. Tea tree oil should never be applied directly to the skin without dilution, as it can cause irritation or allergic reactions.

Aloe vera gel, similarly priced, may help soothe itching but does not help tackle the malassezia.

Lifestyle factors can also play a role. Stress, fatigue and poor sleep are all known to worsen dandruff, and flare-ups are often reported during periods of illness or emotional strain.

Maintaining a balanced diet and adequate hydration should help boost overall skin health.

While dandruff is the most common cause of an itchy, flaky scalp, it is not the only one. Conditions such as psoriasis and eczema can affect the scalp and may require different treatment. 

Psoriasis typically causes thicker, silvery scales and may also affect areas such as the elbows and knees. Eczema is often associated with dry, sensitive skin elsewhere on the body.

Other causes include irritation or allergic reactions to hair products, head lice — which tend to cause intense itching, particularly behind the ears and at the nape of the neck — and fungal infections such as ringworm, which may lead to patchy hair loss.

Patients whose symptoms do not improve after several weeks of over-the-counter treatment, or who experience significant redness, pain or inflammation, should seek medical advice. Prescription treatments, including steroid scalp lotions, may be required.