Itchy skin
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Skin itching (Latin: pruritus) is an unpleasant sensory sensation evoking the need to scratch. It is one of the most common symptoms reported in dermatology, but it can also accompany numerous internal, neurological, endocrine, and oncological diseases. Contrary to popular belief, itching is not a disease in itself, but a symptom indicating the activation of specialized nerve endings in the skin or disorders of stimulus conduction in the nervous system. It can be localized or generalized, transient or chronic. Persistent itching significantly impairs quality of life, disrupts sleep, lowers concentration, and increases the risk of secondary skin damage and superinfections.
Skin itching - what is it
Pruritus is a complex neuroimmunological phenomenon, in the development of which skin cells, the immune system, and nerve fibers responsible for conducting sensory stimuli are involved. It was previously thought that pruritus was a weaker form of pain. Currently, it is known to be a distinct type of sensation, transmitted by specialized type C nerve fibers and numerous chemical mediators.
Among others, the following are responsible for inducing pruritus:
- histamine,
- interleukins (especially IL-31),
- substance P,
- proteases,
- neuropeptides,
- inflammatory cytokines,
- bile acids,
- endogenous opioids.
Depending on the mechanism of development, several types of pruritus are distinguished:
- dermatological pruritus – resulting from skin diseases,
- systemic pruritus – associated with diseases of internal organs,
- neurological pruritus – caused by damage to the nervous system,
- psychogenic pruritus – accompanying mental disorders,
- mixed pruritus – being the result of the coexistence of several mechanisms.
Pruritus lasting longer than 6 weeks is considered chronic.
Itchy skin - where does it come from
The occurrence of itching is a result of the stimulation of receptors located in the epidermis and dermis. The impulse is conducted through nerve fibers to the spinal cord, then to the thalamus and cerebral cortex, where the conscious perception of itching occurs.
The stimulation of receptors occurs, among other things, as a result of:
- skin inflammation,
- damage to the epidermal barrier,
- skin dryness,
- contact with irritating substances,
- allergic reactions,
- infections,
- metabolic disorders,
- hormonal changes,
- the action of certain medications.
An important mechanism is also the so-called vicious circle of itching. Scratching temporarily reduces the unpleasant sensation, but at the same time, it damages the epidermis, intensifies inflammation and the release of mediators responsible for itching. As a result, the symptoms become increasingly severe.
The worsening of symptoms is also influenced by:
- high temperature,
- hot baths,
- psychological stress,
- sweating,
- dry air,
- wearing irritating fabrics, especially wool.
Itchy skin - cutaneous vs. systemic causes - how to tell them apart
Most commonly, pruritus results from dermatological diseases, however, in some patients it constitutes the first symptom of internal organ diseases. Distinguishing between both groups of causes is of key diagnostic importance.
Most common cutaneous causes
Diseases presenting with pruritus primarily include:
- atopic dermatitis,
- urticaria,
- contact dermatitis,
- psoriasis,
- scabies,
- seborrheic dermatitis,
- lichen planus,
- lichen simplex chronicus,
- bullous diseases,
- fungal infections,
- insect bites.
A characteristic feature is the presence of visible skin lesions, such as erythema, papules, vesicles, scaling, or erosions.
Systemic causes
Pruritus can also be a symptom of internal organ diseases, even if the skin initially appears normal.
It most commonly occurs in the course of:
- chronic renal failure,
- cholestasis and liver diseases,
- iron deficiency anemia,
- polycythemia vera,
- lymphomas, especially Hodgkin's lymphoma,
- thyroid diseases,
- diabetes,
- HIV infection,
- malignancies,
- pregnancy (pruritus of pregnancy),
- adverse drug reactions.
A systemic cause may be indicated by:
- absence of skin lesions,
- generalized pruritus,
- persistence of symptoms despite dermatological treatment,
- nocturnal worsening of symptoms,
- coexistence of weight loss, fever, enlarged lymph nodes, or chronic fatigue.
In such cases, extended diagnostics, including laboratory tests and evaluation of internal organ function, is necessary.
Itchy skin - when it requires urgent diagnostics
Although most cases of itching have a mild course, some situations require prompt medical consultation.
Urgent diagnostics are required for itching:
- persisting for over 6 weeks without an identifiable cause,
- affecting the entire body,
- appearing without skin lesions,
- worsening at night,
- coexisting with jaundice,
- associated with unintentional weight loss,
- accompanying fever or night sweats,
- occurring with enlarged lymph nodes,
- associated with shortness of breath or facial swelling,
- appearing after starting a new medication.
Basic diagnostics of chronic itching may include:
- complete blood count,
- ESR and CRP,
- glucose levels,
- renal function parameters,
- liver function tests,
- bilirubin,
- iron and ferritin levels,
- TSH and thyroid hormones,
- urinalysis,
- antibody testing or imaging studies depending on clinical suspicion.
Diagnosing the cause of itching often requires cooperation between a dermatologist and an internist, allergist, hepatologist, nephrologist, or hematologist.
Itchy skin - how to soothe without scratching
Effective treatment of itching primarily involves eliminating its cause. Regardless of the diagnosis, however, proper skin care and limiting factors that aggravate symptoms are of great importance.
The most important principles of management include:
- daily use of emollients that restore the hydrolipid barrier,
- short baths in lukewarm water,
- using mild cleansing products with a physiological pH,
- avoiding overheating the body,
- wearing breathable cotton clothing,
- maintaining appropriate air humidity,
- regular trimming of fingernails.
Instead of scratching, the following can be helpful:
- cool compresses,
- gently pressing or stroking the itchy area,
- cooling products containing menthol or polidocanol,
- stress reduction techniques.
Depending on the cause, the doctor may use pharmacological treatment including:
- topical glucocorticoids,
- calcineurin inhibitors,
- antihistamines,
- immunomodulating agents,
- medications affecting the conduction of nerve impulses,
- biologic therapy in selected inflammatory skin diseases.
In the case of chronic itching resulting from epidermal barrier damage or inflammatory skin diseases, professional dermatological procedures that support skin regeneration are also used. Depending on the diagnosis, they may include deeply moisturizing treatments that rebuild the epidermal barrier, LED light therapy to help soothe inflammation, and individually selected medical peels performed after the acute phase of the disease is under control. These treatments complement causal therapy and should be qualified by a physician.
