How long does gastroenteritis usually last?

Symptoms typically last 1-2 days for milder cases, though some infections, particularly bacterial ones, can last a week or more.

Is gastroenteritis contagious?

Yes, particularly viral causes like norovirus, which spreads easily through contact with an infected person, contaminated surfaces, or food. Staying home for 48 hours after symptoms clear helps prevent spreading it to others.

What should I eat when recovering from gastroenteritis?

Stick to small, bland meals that are easy to digest, such as toast, rice, or bananas, and avoid fatty, spicy, or acidic foods until you're feeling better.

Can children get dehydrated faster than adults with gastroenteritis?

Yes, babies and young children are at higher risk of dehydration and can become unwell more quickly, so it's important to seek medical advice sooner if you're concerned.

Moles: When to Worry & How to Check Your Skin

Signs of a scalp condition

The signs of a scalp condition typically include a combination of visible skin flakes, persistent itching, redness, or noticeable changes in how oily or dry your scalp feels.

Common symptoms

The specific combination of symptoms you experience provides clues to the underlying cause of your scalp irritation. Visible flakes of dead skin are the most frequent complaint, often accompanied by a persistent itch that can disrupt sleep. You might also notice redness or inflammation across the scalp, greasy or oily patches near the hairline, or small bumps and sores. Recognising these primary symptoms helps determine whether you need a simple shampoo change or a medical review.

Dandruff or dry scalp

Dandruff and a dry scalp are frequently confused, but they have entirely different causes and require different treatments. People often assume that white flakes mean their scalp is too dry, leading them to apply heavy oils that can actually make the problem worse. Dandruff is typically a mild form of seborrhoeic dermatitis. According to the NHS, it is manageable with regular anti-dandruff shampoo. It is caused by an overgrowth of a naturally occurring yeast on the skin, which triggers rapid shedding of skin cells and produces large, oily, yellowish flakes. A dry scalp simply lacks moisture, resulting in small, white, dry flakes.

Feature	Dandruff	Dry scalp
Flake Appearance	Large, oily, yellowish	Small, white, dry
Scalp Condition	Greasy or inflamed	Tight, dry, lacking moisture
Other Symptoms	Intense itching, redness	Mild itching, dry skin on other body parts
Primary Causes	Yeast overgrowth, excess sebum	Weather changes, harsh products, dehydration

5 common scalp conditions

The five most common scalp conditions that cause flaking and irritation are seborrhoeic dermatitis, scalp psoriasis, contact dermatitis, folliculitis, and tinea capitis.

Seborrhoeic dermatitis

Seborrhoeic dermatitis is a common inflammatory skin condition that causes flaky, yellowish scales on oily areas such as the scalp, face, and chest. It is the primary cause of clinical dandruff. The NICE CKS states that simple dandruff represents a mild form of scalp seborrhoeic dermatitis. Symptoms include greasy, yellowish scales or flakes, red and inflamed skin, and persistent itching. The condition is linked to an overgrowth of the Malassezia yeast and the body's inflammatory response to it. Stress, fatigue, and hormonal changes are known triggers that can make symptoms worse.

Scalp psoriasis

Scalp psoriasis is an autoimmune disorder that causes skin cells to build up rapidly, forming thick, silvery-white scales and dry, red patches. The symptoms often include well-defined, thick, silvery scales and dry, cracked skin that may bleed if scratched. Patients often describe an intense itching or burning sensation. Unlike dandruff, psoriasis frequently extends beyond the hairline onto the forehead, neck, or around the ears. It is caused by an immune system dysfunction, with common triggers including infections, periods of high stress, and certain medications.

Contact dermatitis

Contact dermatitis is a type of eczema triggered by direct contact with a substance that causes an allergic reaction or severe irritation. Symptoms include an intensely itchy rash, redness, small bumps or blisters, and sometimes a weeping appearance if the skin is broken. The causes are usually allergic reactions to ingredients in hair dye, fragrances, or preservatives. It can also be triggered by irritants, such as harsh chemicals or sulphates in shampoos that strip the scalp of its protective barrier.

Folliculitis

Folliculitis is the inflammation of hair follicles, often caused by a bacterial or fungal infection, which appears as small, pimple-like bumps. Symptoms include small red or white-headed pimples grouped around hair follicles, itchiness, and sometimes painful pus-filled blisters. This condition is commonly caused by staphylococcus bacteria, but it can also be triggered by yeast overgrowth, friction from tight headwear, or blocked follicles from heavy hair products.

Tinea capitis (scalp ringworm)

Tinea capitis, or scalp ringworm, is a highly contagious fungal infection of the scalp and hair shafts. Symptoms include itchy, scaly, bald patches and black dots where hair has broken off at the scalp surface. Sometimes, it can cause a swollen, inflamed, and painful lesion known as a kerion. It is caused by dermatophyte fungi and spreads easily through direct contact with an infected person or by sharing contaminated items like brushes, hats, and towels.

Scalp condition treatments

The most effective treatment for a scalp condition depends entirely on correctly identifying the cause and selecting the right active ingredients to manage it.

Over-the-counter shampoo ingredients

Medicated shampoos contain active ingredients designed to target the specific causes of scalp conditions, from fungus to skin cell build up. Understanding how these ingredients work can save you time and money.

Ketoconazole: An antifungal agent that reduces yeast on the scalp. It is highly effective for seborrhoeic dermatitis and dandruff.
Selenium sulfide: This acts as an antifungal and also slows down the turnover of skin cells, making it a strong choice for seborrhoeic dermatitis.
Salicylic acid: A keratolytic agent, meaning it helps to soften and remove thick scale. It is particularly useful for scalp psoriasis and thick, stubborn flakes.
Coal tar: This slows the rapid growth of skin cells and reduces inflammation. The BNF (NICE) notes that medicated shampoos containing coal tar are commonly used for both psoriasis and seborrhoeic dermatitis.
Ciclopirox: A broad-spectrum antifungal used for persistent dandruff that does not respond to standard treatments.

Prescription treatments

If over-the-counter options fail to control your symptoms, a GP can prescribe stronger, targeted treatments. For severe seborrhoeic dermatitis, a clinician might recommend a prescription-strength antifungal shampoo. The BNF (NICE) notes that short courses of mild to moderate potency topical corticosteroids can be prescribed to quickly calm active inflammation. For infections like tinea capitis or severe folliculitis, you may need a course of oral antifungal or antibiotic medication to fully clear the infection from the hair follicles.

Adapting treatments for your hair type

Effective treatment also involves considering your hair type, as medicated shampoos can be drying or harsh on the hair shaft.

For dry or curly hair: Apply medicated shampoo only directly to the scalp, leaving it on for the recommended time. Use a rich, moisturising conditioner on the lengths and ends of the hair to prevent dryness.
For colour-treated hair: Ingredients like coal tar and salicylic acid can strip colour or cause unwanted discolouration. Look for gentler formulas or do a patch test first.
For oily hair: Regular washing is crucial to manage excess sebum, which feeds the yeasts that cause dandruff. Lathering a medicated shampoo twice during a wash can help effectively cleanse the scalp.

Lifestyle and prevention tips

Preventing scalp conditions from returning requires a consistent hair care routine, effective stress management, and choosing everyday products that do not irritate your skin.

Hair washing frequency

For oily scalps prone to dandruff, more frequent washing with a medicated shampoo is often necessary. Washing daily or every other day helps to control excess oil and prevent the Malassezia yeast from multiplying. Conversely, if you have a naturally dry scalp, washing less frequently with gentle, hydrating products is key to preserving your natural oils and keeping the skin barrier intact.

Diet and stress management

Stress is a common trigger that can worsen inflammatory skin conditions like psoriasis and seborrhoeic dermatitis. When we are stressed, our bodies release hormones that can increase oil production and trigger inflammation. Finding effective stress-management techniques, such as regular exercise or mindfulness, can have a surprisingly positive impact on your skin. While direct links between specific foods and dandruff are debated, a balanced diet rich in zinc, B vitamins, and healthy fats supports overall skin health and healing.

Everyday hair care products

The products you use daily can either soothe or aggravate a sensitive scalp. Avoid shampoos with harsh sulphates, heavy synthetic fragrances, or drying alcohols, as these can strip moisture and cause irritation. Instead, look for products with non-comedogenic and hypoallergenic labels, which are less likely to clog hair follicles or trigger contact dermatitis. Taking care of your skin from the inside out is important, so you may want to read our advice on managing stress to support your overall wellbeing.

When to see a doctor

You should consult a GP for a scalp condition if your symptoms are severe, painful, or do not improve after trying over-the-counter medicated shampoos for a month.

Red flag symptoms

Please book an appointment with a doctor if you experience any of the following:

Severe, persistent itching that disrupts your sleep or daily life.
Painful, bleeding, or weeping sores on the scalp.
Patches of unexplained hair loss.
Symptoms that have not improved after four weeks of using an appropriate medicated shampoo.
Signs of an active infection, such as visible pus, swelling, or heat radiating from the scalp. The NHS advises that persistent, very itchy, red or swollen scalps always warrant a medical review.

Preparing for a GP appointment

To get the most out of your consultation, make a few notes beforehand. Write down your symptoms, how long you have had them, and exactly which treatments or shampoos you have already tried. If you know of any triggers, such as stress or new hair products, mention these too. In our experience as clinicians, it is very helpful if you take clear, well-lit photos of your scalp when your symptoms are at their worst, as this helps the doctor assess the inflammation visually. If you are struggling with a persistent scalp issue, book an online GP appointment with one of our doctors today.

Conclusion

Correctly identifying your specific scalp condition is crucial. Do not assume all flakes are simple dandruff. Understanding the active ingredients in medicated shampoos helps you buy the right product for your exact symptoms, whether you need an antifungal agent or something to soften thick scales. Consistency with your chosen treatment, alongside supportive lifestyle habits like managing stress and washing at the right frequency, is key to long-term management.

You can take control of your scalp health today, as effective solutions are available for nearly every condition. If over-the-counter treatments are not working or you are experiencing painful, persistent symptoms, book a convenient online consultation with a Doctor Care Anywhere GP for a clear diagnosis and personalised advice.

The fungus that causes dandruff is called Malassezia globosa, which is a common yeast naturally present on the skin of most adults. However, in some people, it overgrows and triggers an inflammatory response. The NICE CKS guidance confirms that treatments targeting this yeast are the first-line approach for managing the condition.

Coal tar shampoo works for an itchy scalp by acting as a keratoplastic agent. This means it actively slows down the rapid, abnormal growth of skin cells on the scalp. By doing this, it reduces the scaling, thickening, and inflammation associated with both psoriasis and seborrhoeic dermatitis. The BNF (NICE) notes it as a well-established treatment for these chronic conditions.

Your dandruff gets worse in winter because of a combination of environmental factors. Dry indoor heating strips moisture from the skin, exacerbating a dry scalp. At the same time, colder outdoor air and less exposure to sunlight can worsen the inflammatory response in seborrhoeic dermatitis, causing yeast to thrive and flaking to increase.

Whether ketoconazole or selenium sulfide is better for severe dandruff depends on your symptoms, though both are highly effective antifungal ingredients. Ketoconazole is often considered a first-line treatment for moderate to severe dandruff because of its targeted action against specific yeasts. A Cochrane review concluded that antifungal shampoos like ketoconazole improve dandruff significantly.

Dandruff and Scalp Conditions: Causes and Treatment