The U.S. Food and Drug Administration says there's no reason to believe that the coloring added to sodas is unsafe. But the agency is taking another look just to make sure.

The agency's announcement comes in response to a study by Consumer Reports that shows 12 brands of soda have varying levels of 4-methylimidazole — an impurity found in some caramel coloring.

Schizophrenia is caused by a large number of rare genetic mutations rather than a few, easily-identifiable faulty genes, said scientists who compiled the world's largest database on the debilitating disorder.

Two studies published Wednesday in the journal Nature said the genetic triggers for the mental illness that affects about one in 100 people were far more complex than previously thought.

Taking over-the-counter medication to reduce a fever might help a person to feel better, but may also be increasing the spread of the virus, according to a new Canadian study.

Higher body temperatures help to kill viral and bacterial infections and prevent bacteria and viruses from replicating.

After the failure of two novel drugs using antibodies to fight the buildup of brain plaque in Alzheimer's patients, scientists said Wednesday they have learned lessons for the future.

The biologic drugs solanezumab, by pharmaceutical giant Eli Lilly, and bapineuzumab, by Johnson and Johnson, made it to phase III trials and were taken by thousands of patients, according to a full report on the research published in the New England Journal of Medicine.

They quibble, joke and share knowing looks, finishing each other's thoughts and making snide comments — like many sisters. But a recent heated argument was unlike any other they've had, and it ended in a most surprising way.

For months, 71-year-old Irma Myers-Santana and her younger sister, Anna Williamson, 69, had been debating who more urgently needed a lung transplant, each wanting the other to go first. Earlier this month, though, the sisters ended up in the same operating room, each getting one lung from the same donor in what doctors at Houston Methodist Hospital say is a first for their facility.

Billionaire software baron turned philanthropist Bill Gates has warned that violence in Nigeria and Pakistan could set back his goal of eradicating polio by 2018.

Last year, The Bill and Melinda Gates Foundation -- a charity that funds medical research and vaccination drives -- made wiping out the crippling disease in the next six years its top priority.

Consumers may expect that medical treatments approved for the U.S. market are safe and thoroughly tested, but a study out Tuesday said that is not always the case.

Some drugs undergo more rigorous testing than others, while most are never compared to existing treatments to see if they are better or worse, said the study by researchers at Yale University.

Heart-attack patients admitted to hospital at night or on weekends run a five-percent higher risk of dying than those treated during regular hours, researchers said on Tuesday.

In the United States alone, this translates to an extra 6,000 deaths per year, they reported in the British Medical Journal (BMJ).

A United Nations envoy warned Wednesday that cholera deaths in Haiti will surge and spread to other countries unless more funds are found to battle the epidemic.

More than 8,330 people have already died from cholera, that started in 2010 and many blame on U.N. peacekeepers based in the impoverished Caribbean nation.

Sunlight may help to reduce high blood pressure, a danger factor for heart attacks and stroke, a study published in a specialist journal said on Monday.

British researchers found exposure to sunlight alters the level of nitric oxide in the skin, dilating blood vessels and thus easing hypertension.