The truth about itching

Understanding and Managing Skin Itching

Itching, medically known as pruritus, is an uncomfortable sensation that prompts the desire to scratch. It is a common problem with a wide range of various potential causes, ranging from skin conditions to systemic diseases. In this article we are delving into the truth about itching, we will look into the mechanisms of itching, explore its causes, and provide insights into preventive and therapeutic strategies.

The Mechanisms of Itching

Itching is a complex process that involves the skin, nervous system, and brain. The sensation is primarily mediated by nerve fibers in the skin called C-fibers, which transmit signals to the spinal cord and then to the brain. Several mediators, including histamine, cytokines, and neuropeptides, play crucial roles in this process (1).

Histamine, released by mast cells in response to certain stimuli such as allergens or irritants, binds to receptors on nerve endings, initiating the itch sensation. Cytokines and neuropeptides, released during inflammation or skin damage, can also stimulate itch receptors (2).

Neuropathic itch occurs when there is damage to the nervous system itself, leading to persistent and sometimes intense itching. This type of itch is often seen in conditions like multiple sclerosis, shingles, or post-stroke syndromes (3).

Common Causes of Itching

The truth about itching, is that there are wide array of causes for itchy skin. We will now look into each one in detail.

Dermatological Causes

Dermatological causes refer to skin-related conditions or issues that result in symptoms like itching, redness, or irritation. These causes originate directly from the skin itself, rather than from internal diseases or neurological problems. Examples include eczema, psoriasis, dry skin (xerosis), and contact dermatitis.

In simpler terms, it means the itch or problem is coming from the skin due to irritation, inflammation, or other skin disorders.

1. Dry Skin (Xerosis): One of the most common causes of itching, particularly in older adults, is dry skin. It can result from environmental factors such as low humidity, excessive bathing, and use of harsh soaps (4).
2. Eczema (Atopic Dermatitis): A chronic condition characterized by red, itchy, and inflamed skin. Eczema is often triggered by allergens, stress, or irritants (1).
3. Psoriasis: An autoimmune disorder that leads to rapid skin cell turnover, resulting in thick, scaly patches that can itch intensely (5).
4. Contact Dermatitis: An allergic or irritant reaction to substances such as cosmetics, soaps, or certain plants, leading to localized itching and rash (6).

Systemic Causes

Systemic causes refer to conditions or diseases that affect the entire body (or multiple systems within the body) and can lead to symptoms like itching. Unlike dermatological causes, which originate from the skin, systemic causes are internal and often involve organs or bodily systems, such as the liver, kidneys, blood, or thyroid.

In short, systemic causes are internal problems in the body that can trigger itching or other symptoms in the skin.

1. Liver Disease: Conditions like cholestasis can lead to a build-up of bile acids in the skin, causing severe itching (7).
2. Kidney Failure: Uremic pruritus is a common issue in chronic kidney disease, where toxins accumulate in the body and lead to itching (8).
3. Thyroid Disorders: Both hyperthyroidism and hypothyroidism can cause itching, often related to dry skin and changes in blood flow (9).
4. Blood Disorders: Conditions such as polycythemia vera can cause itching, particularly after a hot bath or shower (9).

Neurological and Psychogenic Causes

The truth about itching is that it can also have neurological and psychogenic causes. These refer to conditions where itching is triggered by problems in the nervous system or psychological factors, rather than being caused by a skin issue or internal organ dysfunction.

1. Neuropathic Itch: Caused by damage to the nervous system, as seen in conditions like shingles, multiple sclerosis, or post-stroke syndromes (2).
2. Psychogenic Itch: Linked to psychological factors such as stress, anxiety, or obsessive-compulsive disorders. It can occur without any apparent physical cause (3).

Neurological Causes

These are itching problems related to the nervous system, where damage or dysfunction in the nerves themselves causes the sensation of itch. For example:

• Neuropathic itch occurs when nerves are damaged (due to conditions like shingles, multiple sclerosis, or nerve injury, or post-stroke syndromes), sending abnormal signals that lead to persistent itching. (2)
• Central nervous system disorders, like a stroke, can disrupt normal nerve signaling, causing abnormal itching sensations.

Psychogenic Causes

These are related to psychological factors, meaning that the itching is linked to mental health or emotional conditions:

• Stress, anxiety, and depression can cause or worsen itching, often due to psychological triggers rather than any physical skin problem.
• Obsessive-compulsive disorder (OCD) or somatic symptom disorder may involve sensations of itch without an underlying physical cause, often triggered by emotional or mental factors.

In short, neurological causes are related to nerve or brain issues, while psychogenic causes are linked to emotional or mental health factors.

Prevention and Treatment of Itching

Preventive Strategies

The truth about treating itching, is that there are various ways to treat, manage or even prevent itching. Once you understand why you are itching (the underlying cause), it is easier to find the most appropriate treatment.

1. Moisturization: Regular use of emollients and moisturizers can help maintain skin hydration and prevent dryness-induced itching (4).
2. Avoiding Irritants: Identifying and avoiding allergens or irritants, such as certain soaps, fabrics, or foods, can prevent contact dermatitis and eczema flare-ups (6).
3. Temperature and Humidity Control: Maintaining a moderate indoor temperature and using humidifiers can prevent skin dryness and associated itching (4).

Topical Treatments

1. Corticosteroids

Pros:

• Very effective for reducing inflammation, redness, and itching quickly.
• Available in different strengths, suitable for mild to severe symptoms.
• Easy to apply directly to the affected area.

Cons:

• Long-term use can cause skin thinning, stretch marks, and discoloration.
• May not be effective for all types of itching.
• Prolonged use can lead to steroid resistance, reducing effectiveness.

2. Calcineurin Inhibitors (e.g., tacrolimus, pimecrolimus)

Pros:

• A good alternative to corticosteroids for long-term use, especially on sensitive areas like the face and eyelids.
• Does not cause skin thinning.
• Effective for eczema and reducing inflammation.

Cons:

• Can cause a burning or stinging sensation upon application, especially at first.
• More expensive compared to corticosteroids.
• Long-term safety is still being monitored due to potential cancer risk concerns.

3. Antihistamines

Pros:

• Useful for itch caused by histamine release, such as allergic reactions.
• Over-the-counter options are widely available and easy to use.
• Oral antihistamines can also help with sleep if itching disrupts it.

Cons:

• Less effective for chronic itching caused by conditions like eczema or psoriasis.
• Topical antihistamines may cause skin irritation in some individuals.
• Oral antihistamines can cause drowsiness (first-generation antihistamines).

Systemic Treatments

1. Immunosuppressants (e.g., cyclosporine, methotrexate)

Pros:

• Effective for severe cases of eczema or psoriasis that don’t respond to topical treatments.
• Helps reduce inflammation and immune system overactivity.
• Provides relief for chronic conditions.

Cons:

• Increases the risk of infections due to suppressed immunity.
• Can have significant side effects, such as liver or kidney damage, nausea, and fatigue.
• Requires regular monitoring through blood tests.

2. Biologics

Pros:

• Specifically target immune system pathways causing inflammation, providing effective relief for moderate to severe eczema or psoriasis.
• Generally well-tolerated with fewer side effects than traditional immunosuppressants.
• Can improve overall quality of life for those with chronic, severe conditions.

Cons:

• Very expensive and may not be accessible to everyone.
• Requires regular injections or infusions, which can be inconvenient.
• Increases susceptibility to infections and may not be suitable for all patients.

Summary of treatments

Each treatment approach offers benefits and has its limitations. Topical treatments are often the first line of defense due to their convenience and targeted relief, while systemic treatments are reserved for more severe or persistent cases. Careful consideration of the patient’s condition, side effects, and long-term needs is essential when choosing the best therapy.

Conclusion

The truth about itching is that it is a multifaceted symptom that can significantly impact quality of life. Understanding the underlying mechanisms and identifying the root cause are crucial for effective management. Whether the itch is due to a dermatological condition, systemic disease, or neurological issue, there are various preventive and therapeutic strategies available. By maintaining skin hydration, avoiding known irritants, managing stress, and utilizing appropriate medical treatments, individuals can effectively manage and alleviate itching.

References

1. Mayo Clinic. “Itchy Skin (Pruritus) – Symptoms and Causes.” Mayo Clinic. https://www.mayoclinic.org/diseases-conditions/itchy-skin/symptoms-causes/syc-20355006
2. Medical News Today. “Neuropathic Itch: Symptoms, Causes, and Treatments.” Medical News Today. https://www.medicalnewstoday.com/articles/neuropathic-itch
3. American Academy of Dermatology. “How to Relieve Uncontrollably Itchy Skin.” AAD. https://www.aad.org/public/everyday-care/itchy-skin/itch-relief/relieve-uncontrollably-itchy-skin
4. Healthline. “Itching: Causes, Diagnosis, and Treatment.” Healthline. https://www.healthline.com/health/itching
5. NHS Inform. “About Itchy Skin.” NHS Inform. https://www.nhsinform.scot/illnesses-and-conditions/skin-hair-and-nails/itchy-skin/about-itchy-skin/
6. WebMD. “Why So Itchy? Causes of Itchy Skin.” WebMD. https://www.webmd.com/skin-problems-and-treatments/why-so-itchy
7. Pfizer. “Bodily Functions Explained: Itch and Scratch.” Pfizer. https://www.pfizer.com/news/articles/bodily_functions_explained_itch_and_scratch
8. MedlinePlus. “Itching.” MedlinePlus. https://medlineplus.gov/itching.html
9. NHS Inform. “Causes of Itchy Skin.” NHS Inform. https://www.nhsinform.scot/illnesses-and-conditions/skin-hair-and-nails/itchy-skin/causes-of-itchy-skin/