Ah, spring. Grass growing, flowers blooming, trees budding. For those with allergies, though, this explosion of new life probably inspires more dread than joy. So what's behind this annual onslaught of mucus? Eleanor Nelsen explains what...

Stress isn't always a bad thing; it can be handy for a burst of extra energy and focus, like when you're playing a competitive sport or have to speak in public. But when it's continuous, it actually begins to change your brain. Madhumita...

It's a common misconception that stomach ulcers are caused by emotional upset, psychological distress, or spicy food. Yet no convincing study has ever demonstrated that these factors directly cause ulcer disease. So what does cause...

Colon cancer is one of the leading causes of cancer and cancer death in the world. It is also one of the most preventable types of cancer, as it often takes about ten years for a small polyp to grow and develop into a cancerous one. So...

An estimated 20 million cases of blindness worldwide are caused by cataracts, a curable condition affecting the lens that focuses images onto the eye's retina. But how are cataracts formed, and how can we prevent them? Andrew Bastawrous...

Beneath your ribs, you'll find, among other things, the pancreas -- an organ that works a lot like a personal health coach. Emma Bryce explains how this organ controls your sugar levels and produces a special juice that releases the...

We tend to think of blindness as something you're born with, but with certain genetic diseases, it can actually develop when you're a kid, or even when you're an adult. But could blind eyes possibly regenerate? David Davila explains how...

More than 300 million people around the world suffer from asthma, and around 250,000 people die from it each year. But why do people get asthma, and how can this disease be deadly? Christopher E. Gaw describes the main symptoms and...

Obesity is an escalating global epidemic. It substantially raises the probability of diseases like diabetes, heart disease, stroke, high blood pressure, and cancer. But what is the distinction between being overweight and being obese?...

Every two seconds, someone in the world has a stroke. One out of every six people will have a stroke at some point in their lives. Strokes deprive brain cells of oxygen and are one of the most common causes of death, and a leading cause...

The ability to recognize sounds and identify their location is possible thanks to the auditory system. That's comprised of two main parts: the ear, and the brain. The ear's task is to convert sound energy into neural signals; the brain's...

In 2008, something incredible happened: a man was cured of HIV. In over 70 million HIV cases, this was a first, and, so far, a last, and we don't yet understand exactly how he was cured. But if we can cure people of various diseases,...

Cancer usually begins with one tumor in a specific area of the body. But if the tumor is not removed, cancer has the ability to spread to nearby organs as well as places far away from the origin, like the brain. How does cancer move to...

There are a number of scenarios that can make us sweat_including exercise, eating spicy foods, and nervousness. But how does this substance suddenly materialize, and what exactly is its purpose? John Murnan explores the science behind...

Language is an essential part of our lives that we often take for granted. But, if the delicate web of language networks in your brain became disrupted by stroke, illness, or trauma, you could find yourself truly at a loss for words....

Human bodies aren't built for extreme aging: our capacity is set at about 90 years. But what does aging really mean, and how does it counteract the body's efforts to stay alive? Monica Menesini details the nine physiological traits that...

The things we eat and drink on a daily basis can impact our health in big ways. Too many carbohydrates, for instance, can lead to insulin resistance, which is a major contributor to cardiovascular disease and Type 2 Diabetes. But what...

Today, glasses help millions of people with poor vision be able to see clearly. But how? Andrew Bastawrous and Clare Gilbert help unravel the answer by explaining refraction - the ability of a transparent medium, like glass, water, or...

Dyslexia affects up to 1 in 5 people, but the experience of dyslexia isn't always the same. This difficulty in processing language exists along a spectrum -- one that doesn't necessarily fit with labels like "normal" and "defective."...

Approximately seven million people around the world die from heart attacks every year. And cardiovascular disease, which causes heart attacks and other problems like strokes, is the world's leading killer. So what causes a heart attack?...

The biggest kidney stone on record weighed more than a kilogram and was 17 centimeters in diameter. The patient didn't actually swallow a stone the size of a coconut; kidney stones form inside the body. So how do they grow in the first...

The vast majority of people who've lost a limb can still feel it - not as a memory or vague shape, but in complete lifelike detail. They can flex their phantom fingers and sometimes even feel the chafe of a watch band or the throb of an...

We've harnessed electricity, sequenced the human genome, and eradicated smallpox. But after billions of dollars in research, we haven't found a solution for a disease that affects more than 14 million people and their families at any...

Originally discovered by accident, X-rays are now used about 100 million times a year in clinics around the world. How do these magic eyes work? Ge Wang details the history and mechanics of the X-ray machine and CT scanners.