It seems simple enough: When you itch, you scratch. But scratching itchy skin often makes the itch worse, and can set off an itch-scratch cycle.

Q: What causes itchy skin?

A: Itchy skin can be the result of a nearly endless number of possible causes, ranging from skin conditions, such as eczema or poison oak, to internal diseases.

Q: What conditions are associated with itch and itching?

A: Dry skin is the most common culprit for causing itch in skin that has no obvious signs of rash or other changes.

These conditions may also cause itchy skin:

• Skin conditions and rashes, such as scabies, lice, chickenpox, hives, psoriasis, eczema (dermatitis).

• Internal disorders, such as celiac disease, liver problems, kidney failure, anemia, certain cancers, and thyroid dysfunction. These conditions may produce itch over the entire body with no outward changes in the skin (except for the scratched areas).

• Irritants and allergens can irritate the skin and cause itching

• Food allergies

• Certain medications, like antibiotics or antifungals, can provoke rashes in some people.

• Pregnancy

Q: How do I know if I need to see my dermatologist?

A: If your itch lasts more than a couple weeks, is severe enough to disrupt your everyday activities or sleep, has no obvious cause, or affects your whole body, it’s time to see your dermatologist. You should also see a doctor if the itch occurs with other symptoms, such as fatigue, weight loss, bowel or urinary problems, fever or skin redness.

Q: Are there treatments for itching?

A: Yes, there are several treatments, depending on the cause of your itching:

• Medications, including topical corticosteroid creams or oral antihistamines

• Wet dressings, in which you apply medicated cream to the itchy areas and cover them with moist cotton material—the dampness of the dressing helps the skin absorb the medication.

• Treating any underlying disease. If your doctor has identified an underlying disease that’s causing the itch, then he or she will treat that disease

• Light therapy (phototherapy). This involves exposing the affected areas to certain wavelengths of ultraviolet (UV) light in multiple sessions until the itch is resolved

For immediate, at-home relief, you might want to try certain topical medications, such as creams, ointments and lotions containing lidocaine, benzocaine, menthol, camphor or calamine. However, these solutions should only be used in the short term. If your itch persists, call a dermatologist.

Dr. Oswald Lightsey Mikell, certified by the American Board of Dermatology and the American Board of Cosmetic Surgery, is the owner of Dermatology Associates of the Lowcountry.