Your back has been itchy for days, and nothing you do seems to make it better. You thought it was a case of dry skin, but moisturizer doesn't seem to do the trick.
Severe or constant itching can be agonizing. In addition to the discomfort, it can lead to insomnia, anxiety or depression. And scratching the same area over and over can cause your skin to become thick and leathery — making the itch even more difficult to treat.
It makes sense that you want to identify the cause of your itch and seek treatment.
The many causes of itchy skin
While dry skin is often to blame for an itch, there are actually hundreds of possible causes of constant itching. In many cases there may even be more than one cause. For example, using harsh soap combined with changes in air humidity may cause itching.
When itching occurs with a rash (including redness, bumps, blisters, hives or scaling), it's typically due to a skin-related cause.
Possible causes of rash-related itching include:
- Dry skin. This is a common cause of itchy skin. Your skin might have an ashy appearance or small white flakes or scales. Common causes are frequent bathing with excessive soap — particularly in hot water — and dry air.
- Skin diseases. These may include psoriasis, various forms of skin inflammation (dermatitis), hives, skin infections or skin cancer.
- Infection-related problems. Fungal infections can occur in moist, warm areas, like in body folds or on the feet. Other causes of infection may include scabies, lice or other bugs, and chickenpox or shingles.
- Irritation and allergic reactions. In a condition called contact dermatitis, skin can become inflamed by any number of irritants, like poison ivy, cosmetics, metals, cleaning products or wool.
Less commonly, itching occurs without a rash and may affect all areas of the body. In this case, the cause may be internal.
These causes may include:
- A disease. Liver and kidney disease, iron deficiency anemia, thyroid problems, cancers like leukemia or lymphoma, and certain autoimmune diseases like scleroderma or Sjogren's disease may cause itching.
- Medicine side effects. Itching is a side effect of many medicines, with opioid pain medicine being a common culprit. Itching can start within a few weeks or months of starting a new medicine or increasing a dosage.
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Nerve problems. A pinched, damaged or irritated nerve can cause the sensation of itching. This may occur in a widespread or focused area, like your forearm, central back or anal area.
Nerve damage due to diabetes, multiple sclerosis and shingles are other possible causes.
A pinched or irritated nerve in the spine, postherpetic neuralgia that can develop after a shingles outbreak, nerve damage due to diabetes, and stroke or nerve-damaging diseases like multiple sclerosis are other possible causes.
- Mental health conditions. Stress, depression, anxiety disorders or other issues may be associated with chronic itching.
- No cause. Unfortunately, sometimes no underlying cause can be found. This commonly occurs in older adults.
What you can do
Treating just about any form of chronic itch means tackling common causes first. You may want to try a gentler cleaner, or moisturize dry skin.
If that isn't helpful, the next step is treating or addressing any underlying cause. Whether it's a skin disease, infection or medicine side effect, addressing the underlying cause can make the itching go away or significantly reduce it.
Your doctor may also recommend options for quicker relief, like:
- A steroid cream like hydrocortisone. This may be helpful for itchy skin that's also inflamed.
- Cooling creams like menthol, camphor or calamine. A cold pack may also help relieve an itch.
- Creams or ointments with calcineurin inhibitors. This is a prescription medicine that affects the immune system.
With itching that appears to be caused by nerve problems, over-the-counter medicine called capsaicin cream may help. It's made from the seeds of hot chili peppers. Oral drugs that act on the nervous system, like antidepressants and anti-seizure drugs, can also be effective.
When a cause can't be found
When your doctor can't detect the cause of persistent itching, phototherapy may be recommended. This involves repeatedly exposing your skin, over weeks, to specific wavelengths of ultraviolet light.
Phototherapy is an effective treatment for certain skin diseases, like psoriasis. It can also be effective for certain types of itching in which no skin rash is visible.
If you have to live with a certain amount of itching, coping mechanisms like relaxation and habit reversal training can help. Cognitive behavioral therapy can also be useful in breaking the itch-scratch cycle and enabling better sleep.