Seborrheic dermatitis of the scalp and hair loss: causes, symptoms, treatments and advice

Seborrheic dermatitis of the scalp is sometimes accompanied by hair loss.
What are the causes? Who may be affected? What should you do if this happens and what treatment is most appropriate? Find out in this article.

Causes of seborrheic dermatitis of the scalp

Seborrheic dermatitis of the scalp is a common skin condition.
It manifests itself as red patches covered with yellowish, sticky scales. These scales are formed by a mass of dead cells, as if the skin on the scalp were renewing itself too quickly, creating a sort of thick dandruff. These symptoms are often accompanied by itching, which can make everyday life very uncomfortable.
All these signs are the result of an inflammatory reaction on the scalp.

Although the exact causes of seborrheic dermatitis are not yet fully understood, several key factors have been identified:

• excess sebum in areas rich in sebaceous glands, which encourages proliferation of the yeast Malassezia.
• a release of fatty acids produced by the yeast Malassezia, which irritate the skin, as if creating microscopic burns that trigger inflammation.

Excess sebum and the proliferation of Malassezia cause localised inflammation on the scalp, leading to the appearance of red patches, scales and itching. This is the body's response to an imbalance in the skin, also known as cutaneous dysbiosis ⁽¹⁾.

Although seborrheic dermatitis is neither serious nor contagious, it cannot be completely cured. It is a chronic inflammatory condition, which means that it can recur periodically. Regular care is necessary to reduce symptoms, prevent breakouts and limit recurrences.

Impact of seborrheic dermatitis on hair loss

Seborrheic dermatitis of the scalp and hair loss can sometimes go hand in hand for the same person ⁽²⁾.
Scientific studies show that this type hair loss could be linked to a phenomenon called "seborrheic folliculitis". In other words, it is an inflammation of the hair follicle (the small structure from which each hair grows). When this follicle is inflamed, it can weaken the hair and lead to hair loss, a phenomenon known as alopecia ⁽³⁾.

Think of your scalp as a garden. If the soil is too saturated with water (or in this case, sebum), the roots of the plants (in this case, your hair) can lack oxygen. Similarly, when the scalp is clogged with excess sebum and thick scales, it can "suffocate" the hair, preventing it from being oxygenated and nourished properly. This can ultimately lead to hair loss, which can also be delayed, because the roots have not had enough air to breathe properly.

In severe cases of seborrheic dermatitis with very thick, adherent scales, the accumulation of sebum in the hair follicles can damage the hair's health, leading to hair loss ⁽⁴⁾.

Aggravating and triggering factors

Seborrheic dermatitis of the scalp and hair loss share a number of aggravating and triggering factors ⁽²⁾:

• Genetic predisposition: if your parents or grandparents suffered from these problems, you may be more likely to develop them too.
• Hormonal imbalances, particularly during hormonal changes at puberty, during pregnancy, or as a result of illness or hormone therapy.
• Physical or emotional stress ⁽⁵⁾
• Exposure to aggressive agents (styling products, aggressive shampoos, rubbing, etc.).
• An unbalanced diet lacking in essential nutrients can contribute to deficiencies, affecting the health of both the scalp and the hair.

And these factors often do not work alone. They can interact with each other, creating a domino effect that aggravates both seborrheic dermatitis of the scalp and hair loss.
It's as if all these elements combine to attack your scalp and hair simultaneously, making the problem more difficult to manage.

Choosing the right treatment

When you’re faced with both seborrheic dermatitis of the scalp and hair loss, it’s often advisable to start by treating the scalp. The aim of this is to reduce excess sebum and limit the proliferation of Malassezia yeast, thereby rebalancing the skin microbiome ⁽¹⁾. This helps to reduce inflammation, calm itching and soothe the scalp.

To use the garden analogy again: when the soil is healthy and well maintained, the plants (your hair) grow better. Hair care products specifically formulated to treat seborrheic dermatitis are therefore the best options.

Depending on the advice of a healthcare professional, you may also incorporate a targeted hair loss treatment.

Shampoos

There are two types of shampoo for treating seborrheic dermatitis: shampoos prescribed by a doctor and shampoos you can buy directly from a chemist or beauty store.
The doctor may recommend the use of just one type or a combination of the two.
Dermo-cosmetic treatment shampoos contain keratolytic, antifungal and anti-inflammatory active ingredients. They are easy to spot on the shelf thanks to the initials D.S., which stand for Dermite Séborrhéique (Seborrheic Dermatitis).
Follow the application protocol carefully and respect the duration of the treatment to ensure lasting efficacy and minimise relapses.

Topical medicine

To treat seborrheic dermatitis of the scalp and hair loss, a specialist doctor may prescribe medicine to be applied locally in the form of shampoos or creams.
These treatments target Malassezia yeast by using antifungal agents such as ketoconazole, which is highly effective. They can be used alone or in combination with dermocorticoids to reduce inflammation. 

Oral medicine

If the symptoms of seborrheic dermatitis persist despite local treatments, it is quite possible that your doctor will propose an oral treatment for a more complete action, again based on antifungal and anti-inflammatory agents.

In cases of seborrheic dermatitis of the scalp combined with hair loss, your doctor may also suggest a hormonal assessment to better understand the underlying causes and adapt treatment accordingly. 

Natural treatments

Natural solutions can also be used to complement conventional medical treatments. For example, certain plants used in phytotherapy, such as tea tree oil, Cayenne quinine (quassia amara), or nightshade (solanum chrysotrichum), have been shown to have beneficial effects ⁽⁶⁾. 

However, it is essential to consult a health professional before starting any natural treatment to avoid contraindications or allergies. It is particularly important to be aware that an essential oil:

• should be mixed with a vegetable oil or incorporated into the treatment shampoo.
• should be used according to the dose recommended by a healthcare professional.

Keep your scalp healthy to look after your hair

The scalp, like the skin, acts as a protective barrier. To preserve your hair, you need to take care of it:

• Opt for hair care products that are adapted to the scalp and its needs. That means gentle shampoos for frequent use or, in the event of imbalance, specific treatment shampoos.

Any doubts? Do your own online diagnosis to find out which skincare routine is best suited to your needs.

• Use brushes made from natural materials and avoid scratching the scalp repeatedly. Leave hair to air dry as much as possible. If you use a hairdryer, do so on a low temperature to avoid drying out the scalp.
• Avoid using irritating products on the scalp (styling gel, hairspray, hair dyes, etc.). After swimming in a pool, rinse your hair thoroughly to avoid prolonged contact with chlorine.

More generally, it’s important to consider that your lifestyle is an important factor:

• A healthy, balanced diet that’s rich in fibre (vegetables, fruit, pulses, etc.) and essential fatty acids (small oily fish, vegetable oils rich in omega 3, etc.) is recommended. 
• It’s important to get regular exercise and learn how to better manage stressful periods by seeking support if necessary.
• Of course, regular medical check-ups are essential for preventing any long-term health issues (hormonal imbalances, weight, etc.).