Scalp eczema: atopic and contact dermatitis, and the hair loss question

An itchy, red, flaky scalp is easy to dismiss as dandruff. Sometimes it is. But the scalp can also be affected by eczema, a group of conditions that make skin dry, inflamed and itchy. The two types that matter most on the scalp are atopic dermatitis, the long-running kind of eczema that often starts in childhood, and contact dermatitis, a reaction to something that touches the skin, such as a hair dye, shampoo ingredient or hair loss treatment. People with scalp eczema often ask the same question: is this going to make my hair fall out? This article explains how scalp eczema shows up, what tends to trigger it, how it is told apart from look-alike conditions, what treatment usually involves, and what is known about its link with hair loss.

(This article is general health information and is not a substitute for personal medical advice.)

Short answer

Scalp eczema usually means atopic dermatitis or contact dermatitis affecting the scalp. Both cause itch, redness or discolouration, dryness and scaling, and contact dermatitis can also blister or burn ^{1 2 3}. On the scalp, contact allergy is most often linked to hair dyes, shampoos and conditioners, with para-phenylenediamine (PPD), nickel and fragrance among the commonest allergens ^{3 4}. Topical minoxidil is also a recognised cause of scalp contact dermatitis ⁵. Eczema itself does not usually destroy hair follicles, but scratching and inflammation can make hair look thinner, and atopic dermatitis is linked with a higher chance of alopecia areata, an autoimmune form of patchy hair loss ⁶. Treatment focuses on calming the skin, often with emollients and topical corticosteroids, and on finding and avoiding triggers, with patch testing if allergy is suspected ^{1 2}. See a doctor if the scalp is weeping, crusted, painful, or losing hair in patches.

What "scalp eczema" covers

"Eczema" is the name for a group of conditions that make skin dry and irritated ². On the scalp, a few different patterns are common, and they can overlap.

Atopic dermatitis (atopic eczema). A common, long-term skin condition that causes itchy skin. It affects people of all ages but is most common in young children. It often runs in families and is linked to asthma and hay fever. It tends to come and go, with flare-ups and calmer periods ¹. On the scalp it can appear as itchy, dry, scaly or thickened patches, sometimes with cracking, crusting or bleeding from scratching.

Contact dermatitis. A type of eczema triggered by contact with a particular substance. It can be irritant, where a substance directly damages the outer layer of skin, or allergic, where the immune system reacts to something the skin has become sensitised to. Irritants such as soaps and detergents are the more common cause overall, while allergic contact dermatitis can be triggered by substances in cosmetics or by metals such as nickel ².

Seborrhoeic dermatitis. Often grouped with eczema, this causes greasy, yellowish or white flakes and redness on oily areas such as the scalp, eyebrows and sides of the nose ^{7 8}. It is not the same as atopic or contact dermatitis, but it is one of the main look-alikes. See Seborrhoeic dermatitis of the scalp: more than dandruff.

Signs to look for

Common features of eczema on the scalp include:

• itching, sometimes intense, and often worse at night or in the heat;
• dry, flaky or scaly patches;
• red patches on lighter skin, or darker brown, purple or grey patches on darker skin ^{1 2};
• thickened skin in areas that have been scratched for a long time;
• small cracks, scratch marks, crusts or oozing during a flare;
• rash spreading to the hairline, ears, neck or face.

With contact dermatitis, the timing can be a clue. The reaction usually appears within a few hours or days of contact with an irritant or allergen ². If a rash flares a day or two after colouring, or after starting a new shampoo or scalp treatment, that is worth noting. A systematic review of scalp contact allergy found the commonest symptoms and signs were eczematous patches, itch and a burning sensation ³.

Allergic reactions on the scalp often show up most clearly at the edges, such as the hairline, behind the ears, the eyelids and the neck, because the scalp skin is relatively thick and hair-bearing.

What triggers scalp eczema

Triggers for atopic dermatitis

The cause of atopic eczema is not always known. You are more likely to have it if a parent has eczema or if you or a close family member has asthma or hay fever. It can be made worse by contact with allergens or irritants such as soap and detergents, heat or changes in temperature, skin infections, stress and hormonal changes ¹. In a hot, humid climate, sweat and heat under the hair can be a real factor for some people.

Common causes of scalp contact allergy

The scalp is exposed to many products. A systematic review of 99 studies with 3,185 patients found that hair products reported in scalp allergic contact dermatitis were most often hair dyes (41%), shampoos (28%) and conditioners (22%). The commonest patch-test allergens were ³:

• p-phenylenediamine (PPD), found in many oxidative hair dyes;
• nickel;
• fragrance mix;
• balsam of Peru (a fragrance-related allergen);
• cocamidopropyl betaine and a related impurity (foaming agents in shampoos);
• methylchloroisothiazolinone/methylisothiazolinone (preservatives).

A large North American patch-test analysis found that 9.0% of 38,775 tested patients had positive reactions linked to hair care products. People with these reactions were much more likely to have dermatitis mainly on the scalp. PPD was the most frequent relevant allergen, and shampoos and conditioners were the most frequent source of reactions ⁴.

Hair dye is a special case because PPD is a strong sensitiser and reactions can be severe. Read more in Hair dye and hair loss: allergy, breakage and safety. Bleaching powders contain persulfates, which can also cause allergy; see Bleaching and hair loss: breakage, scalp burns and recovery.

Hair loss treatments can cause contact dermatitis too

This matters because people with thinning hair often apply products to the scalp every day. A systematic review on topical minoxidil noted that contact dermatitis is its most commonly reported side effect. Patients typically had redness, itch and more scaling of the scalp. Among those with positive patch tests, 54 reacted to minoxidil itself and 12 to vehicle ingredients. People sensitive to propylene glycol, a common solvent, may be offered a different formulation ⁵.

In a small series of confirmed allergic scalp contact dermatitis at a hair clinic, topical minoxidil was the commonest allergen, followed by PPD ⁹. A hospital study in China that patch-tested people with hair disorders also found that 5% minoxidil products gave a notable rate of positive reactions ¹⁰. These are selected clinic groups, so the numbers do not tell you how likely an average user is to react, but they show that a daily scalp treatment can be the cause of a new rash. See Itchy, flaky scalp on minoxidil: propylene glycol, foam and what to try and Minoxidil side effects: what is common and what needs attention.

Look-alikes: what else could it be?

Several scalp conditions cause itch and scale. Telling them apart affects treatment.

For more detail, see Scalp psoriasis: signs, triggers and treatment basics, Scalp ringworm (tinea capitis): signs and treatment and Itchy scalp: common causes and what to do.

A doctor may look closely with a dermatoscope. A small study described trichoscopic features of allergic scalp contact dermatitis, including redness, white scale and certain blood-vessel patterns, and suggested trichoscopy can help with diagnosis ⁹.

The hair loss question

This is what most people really want to know. The honest answer has several parts.

Eczema itself usually does not destroy hair follicles

Atopic and contact dermatitis are inflammations of the skin's surface layers. They are not scarring hair loss conditions, and once the skin settles, hair usually behaves normally again. Scarring hair loss, where follicles are replaced by scar tissue, comes from different conditions; see Scarring alopecia and lichen planopilaris: why early care matters.

Scratching and inflammation can make hair look thinner

Hard scratching and rubbing put mechanical stress on hair. Over time this can break hairs, leaving short, uneven pieces, especially where itch is worst. The NHS advises not to scratch eczema because it can make it worse, and suggests gently rubbing with a finger instead ¹. Breakage like this is not loss from the root and tends to improve as the itch is controlled. See Hair breakage vs hair loss: how to tell.

During a severe, widespread flare, some people also notice more shedding. Major inflammation, illness or stress can be followed by a period of increased shedding, which usually settles once the trigger is controlled. If shedding continues for months, a doctor should look for other causes.

Atopic dermatitis is linked with alopecia areata

Alopecia areata is an autoimmune condition that causes round or oval patches of hair loss. A 2024 meta-analysis of 29 studies found a two-way association: people with atopic dermatitis were more likely to have alopecia areata, and people with alopecia areata were more likely to have atopic dermatitis. In this analysis, about 11% of people with alopecia areata had atopic dermatitis ⁶.

This does not mean eczema causes alopecia areata. It means the two tend to occur together more often than chance, likely because of shared immune pathways. If you have eczema and notice smooth, round bald patches, that is a reason to see a doctor rather than assuming it is from scratching. See Alopecia areata (patchy hair loss): a clear explainer and Autoimmune conditions and hair loss: lupus, thyroid disease and alopecia areata.

Treatment for eczema can interact with hair, in both directions

Newer treatments for moderate to severe atopic dermatitis include biologic medicines such as dupilumab. Reports have been mixed: some suggest benefit for alopecia areata and others suggest it may trigger it. A large database study found a higher rate of alopecia areata in people with atopic dermatitis using dupilumab compared with matched controls, and the authors recommended scalp checks and patient education ¹². This is a single observational study and does not prove cause, but it is worth knowing. Never stop a prescribed treatment on your own; discuss any new hair loss with your doctor.

Contact allergy and frontal fibrosing alopecia: an open question

Frontal fibrosing alopecia (FFA) is a scarring condition that causes the frontal hairline to recede, mostly in middle-aged women. Some researchers have reported more contact allergy among people with FFA, and chemicals in some leave-on products have been studied, but causation has not been shown ¹³. If you have both scalp or facial dermatitis and a receding front hairline, a dermatologist should assess you.

How scalp eczema is usually treated

Treatment depends on the type and severity, and a doctor should confirm the diagnosis. Broadly:

Calm the skin. The main treatments for atopic eczema are emollients and topical corticosteroids ¹. On the scalp, steroids often come as lotions, gels, foams or medicated shampoos because creams are hard to use through hair. Use them as directed, for the length of time prescribed.

Find and avoid triggers. Contact dermatitis usually improves or clears up completely if the substance causing it is identified and avoided ². That can mean changing shampoo, stopping a hair dye or switching a hair loss product.

Patch testing. If allergy is suspected, a dermatologist can arrange patch testing. A doctor may refer you if the cause cannot be identified or symptoms are not responding to treatment ². Patch testing can show whether you are reacting to an active ingredient such as minoxidil or to something in the vehicle, which affects what you can safely use next ⁵.

Treat infection. Eczema that is blistered, crusty, weeping, painful, swollen or warm, or comes with a fever, may be infected and needs prompt medical care ¹.

For persistent, severe atopic dermatitis. A dermatologist may discuss other options, including newer medicines. These need specialist supervision.

Daily scalp care when you have eczema

• Choose gentle, fragrance-free products. Fragrance and some preservatives are common scalp allergens ^{3 4}.
• Read labels. If you know your allergen, check ingredient lists every time; formulas change. The NHS suggests checking ingredients on products and contacting the manufacturer if needed ².
• Introduce one new product at a time, so you can tell what caused a reaction.
• Rinse well. Leftover shampoo or conditioner can irritate sensitive skin.
• Keep cool. Heat can make eczema more itchy ¹. Avoid very hot water and long blow-drying close to the scalp.
• Do not scratch. Keep nails short and press or gently rub instead ¹.
• Be careful with dye and bleach. If you have reacted before, tell your stylist and doctor. A past reaction to PPD dye is a strong reason to avoid it.
• Be cautious with home remedies. Oils, vinegar rinses and herbal products can irritate or sensitise already inflamed skin.

Hair loss treatment if you also have scalp eczema

Having eczema does not rule out treating pattern hair loss, but it does change the plan.

• If minoxidil makes your scalp itchy and flaky, it may be irritation, allergy, or a flare of existing dermatitis. A doctor can help work out which, sometimes with patch testing ⁵.
• If propylene glycol is the problem, a different formulation may suit you better ⁵.
• Treat active eczema first. Applying treatments to inflamed, broken skin increases the chance of stinging and reaction.
• Oral options may be discussed by a doctor when topical treatment is not tolerated.

For pharmacy products, see Hair loss products at the pharmacy: what to ask the pharmacist.

When to see a doctor

See a doctor if:

• your scalp is weeping, crusted, blistered, painful, swollen or warm, or you feel unwell ¹;
• itch and rash keep coming back or do not improve with gentle care ²;
• you suspect a reaction to hair dye, a shampoo or a hair loss treatment;
• you notice round, smooth bald patches;
• shedding continues for more than a few months;
• your hairline is receding along with redness or scale.

If your face, lips or throat swell or you have trouble breathing after any hair product, get emergency help.

Life in Malaysia

Heat, humidity and sweat are part of daily life in Malaysia, and many people wash their hair often and wear head coverings for much of the day. Both can affect how the scalp feels. Keep the scalp clean and dry, choose gentle products, and let hair dry fully before covering it where possible. Before buying a scalp product, check that it is properly notified; NPRA's cosmetic guidance is a useful starting point ¹⁴. Persistent or severe scalp eczema is best assessed by a registered medical practitioner, ideally a dermatologist; you can check registration on the Malaysian Medical Council register ¹⁵. For non-prescription products, see Hair loss products at the pharmacy: what to ask the pharmacist, and for an overview of hair loss care, see Hair loss treatment in Malaysia: a plain guide to your options.

Bottom line

Scalp eczema is usually atopic dermatitis, contact dermatitis, or both, and it often overlaps with seborrhoeic dermatitis. It causes itch, scale and discomfort, and in contact dermatitis the trigger is often a dye, shampoo, conditioner or scalp treatment, including minoxidil ^{3 5}. Eczema itself rarely destroys follicles, but scratching can break hair, and atopic dermatitis is linked with alopecia areata ⁶. Calm the skin, find the trigger, avoid scratching, and get patch testing if allergy is likely. If you see patchy bald spots or persistent shedding, ask a doctor to look beyond the eczema.

Frequently asked questions

What is scalp eczema?

It usually means atopic dermatitis or contact dermatitis affecting the scalp. Both cause itch, dryness, redness or discolouration and scaling. Seborrhoeic dermatitis is a related look-alike with greasier flakes.

Can scalp eczema cause hair loss?

Eczema itself does not usually destroy hair follicles. Scratching can break hairs and a severe flare may be followed by extra shedding, which usually settles once the skin calms down.

Is eczema linked to alopecia areata?

Yes. A 2024 meta-analysis found that atopic dermatitis and alopecia areata occur together more often than expected. This is an association, not proof that one causes the other.

What commonly causes allergic contact dermatitis on the scalp?

Hair dyes, shampoos and conditioners are the products most often reported. Common allergens include PPD, nickel, fragrance and some preservatives and foaming agents.

Can minoxidil cause scalp eczema?

It can. Contact dermatitis is the most commonly reported side effect of topical minoxidil. The reaction may be to minoxidil itself or to vehicle ingredients such as propylene glycol.

How is scalp contact allergy confirmed?

A dermatologist can arrange patch testing, where small amounts of possible allergens are applied to the skin and checked over several days.

How is scalp eczema treated?

Usually with emollients and topical corticosteroids in scalp-friendly forms such as lotions, foams or medicated shampoos, plus avoiding triggers. A doctor should guide treatment.

When should I see a doctor?

If the scalp is weeping, crusted, painful or swollen, if you feel unwell, if rashes keep coming back, or if you notice round bald patches or shedding that lasts for months.

Educational content. Not medical advice.