What is pellagra?

Pellagra is a disease caused by low levels of niacin, also known as vitamin B-3. It’s marked by dementia, diarrhea, and dermatitis, also known as “the three Ds”. If left untreated, pellagra can be fatal.

While it’s much less common than it used to be, thanks to advancements in food production, it’s still a problem in many developing countries. It can also affect people whose bodies don’t properly absorb niacin.

What are the symptoms?

The main symptoms of pellagra are dermatitis, dementia, and diarrhea. This is because niacin deficiency is most noticeable in body parts with high rates of cell turnover, such as your skin or gastrointestinal tract.

Dermatitis related to pellagra usually causes a rash on the face, lips, feet, or hands. In some people, dermatitis forms around the neck, a symptom known as Casal necklace.

Additional dermatitis symptoms include:

  • red, flaky skin
  • areas of discoloration, ranging from red to brown
  • thick, crusty, scaly, or cracked skin
  • itchy, burning patches of skin

In some cases, the neurological signs of pellagra appear early on, but they’re often hard to identify. As the disease progresses, possible dementia symptoms include:

  • apathy
  • depression
  • confusion, irritability, or mood changes
  • headaches
  • restlessness or anxiety
  • disorientation or delusions

Other possible pellagra symptoms include:

  • sores on the lips, tongue, or gums
  • decreased appetite
  • trouble eating and drinking
  • nausea and vomiting

What causes it?

There are two types of pellagra, known as primary pellagra and secondary pellagra.

Primary pellagra is caused by diets low in niacin or tryptophan. Tryptophan can be converted to niacin in the body, so not getting enough can cause niacin deficiency.

Primary pellagra is most common in developing countries that depend on corn as a staple food. Corn contains niacytin, a form of niacin that humans can’t digest and absorb unless prepared properly.

Secondary pellagra occurs when your body can’t absorb niacin. Things that can prevent your body from absorbing niacin include:

How is it diagnosed?

Pellagra can be difficult to diagnose because it causes a range of symptoms. There’s also no specific test for diagnosing niacin deficiency.

Instead, your doctor will start by checking for any gastrointestinal problems, rashes, or changes in your mental state. They may also test your urine.

In many cases, diagnosing pellagra involves seeing if your symptoms respond to niacin supplements.

How is it treated?

Primary pellagra is treated with dietary changes and a niacin or nicotinamide supplement. It may also need to be given intravenously. Nicotinamide is another form of vitamin B-3. With early treatment, many people make a full recovery and start feeling better within a few days of starting treatment. Skin improvement may take several months. However, if left untreated, primary pellagra usually causes death after four or five years.

Treating secondary pellagra usually focuses on treating the underlying cause. However, some cases of secondary pellagra also respond well to taking niacin or nicotinamide either orally or intravenously.

While recovering from either primary or secondary pellagra, it’s important to keep any rashes moisturized and protected with sunscreen.

Living with pellagra

Pellagra is a serious condition that’s caused by low levels of niacin, due to either malnutrition or an absorption problem. If left untreated, it can cause death. While primary pellagra responds well to niacin supplementation, secondary pellagra can be harder to treat, depending on the underlying cause.