Cancer patients' gray hair unexpectedly turned youthfully dark while taking novel drugs, and it has doctors scratching their heads. Chemotherapy is notorious for making hair fall out, but the 14 patients involved were all being treated with new immunotherapy drugs that work differently and have different side effects. A Spanish study suggests that may include restoring hair pigment, at least in patients with lung cancer. The 14 cases were among 52 lung cancer patients being followed to see whether they developed bad side effects from the drugs — Keytruda, Opdivo and Tecentriq. While most patients did not have a color change, the 14 cases suggest it's not an isolated finding.

Long workdays may be bad for your heart

Working long hours may increase the risk for atrial fibrillation, or irregular heartbeats that can lead to serious cardiovascular complications, a new study in the European Heart Journal found. The researchers began with 85,494 men and women with no record of atrial fibrillation. They assessed working hours at the start, and then followed them for an average of 10 years, defining incidents of atrial fibrillation with medical records and death certificates. They adjusted for many variables and found that the more hours people put in, the greater their risk. Compared with people who worked 35 to 40 hours a week, those who worked more than 55 hours had a 40 percent increased risk of atrial fibrillation. The study wasn't without its limitations, however. Researchers assessed working hours only once among the participants, and the experiment did not account for job type.

Some antibiotics not safe during pregnancy

A large study published in the British Journal of Clinical Pharmacology found that certain antibiotics taken during pregnancy may increase the risk for birth defects. Canadian researchers followed 139,938 mothers of babies born in Quebec from 1998 to 2008, tracking their antibiotic use in the first trimester, and their babies' birth defects. The senior author, Anick Bérard, a professor of epidemiology at the University of Montreal, said that antibiotics in the class called quinolones — ciprofloxacin, levofloxacin and others — are particularly dangerous and should be avoided in pregnancy. But she said: "Infection itself is associated with adverse pregnancy outcomes, and they must be treated. Our study shows that we must think about which antibiotics to use." After adjusting for variables, they found that for some drugs, the increased risk was quite large — for example, doxycycline more than doubled the risk for cardiac abnormalities.