Johnson & Johnson is lowering the recommended top dose of Extra Strength Tylenol to reduce the risk of accidental overdose from acetaminophen. Paul Sakuma/AP hide caption

itoggle caption Paul Sakuma/AP

Bottles of antiretroviral drug Truvada, a medicine used in trials that showed a reduction in transmission of HIV between heterosexuals. Justin Sullivan/Getty Images hide caption

itoggle caption Justin Sullivan/Getty Images

Yasmin birth control pills are among those that contain drospirenone, a synthetic hormone that appears to carry an elevated risk for blood clots. Gnarls Monkey/Flickr hide caption

itoggle caption Gnarls Monkey/Flickr

Mixing antidepressant Paxil and the cholesterol-fighter Pravachol may lead to an unexpected increase in blood sugar, researchers say. Joe Raedle/Getty Images hide caption

itoggle caption Joe Raedle/Getty Images