November 22, 2011: After four decades of use, the U.S. Army is banning the use of mefloquine (an anti-malaria drug) because of side effects. Malaria is a debilitating (and sometimes fatal) disease found in most tropical areas. The medication to prevent it has always been unpleasant, either in terms of taste (no longer a problem) or side effects. These uncomfortable side effects are the big problem now. Sometimes it's a huge problem. Two years ago, PTSD (post-traumatic stress disorder) was found to interact in a fatal way with mefloquine. PTSD sufferers taking mefloquine resulted in more anxiety and suicidal behavior.
Once this interaction was discovered, troops with PTSD could no longer use the mefloquine. This impacted a lot of troops, and prevented them from being sent to some areas (like the Persian Gulf and Afghanistan) where malaria is a risk. The number of troops affected was considerable. In some parts of the world, less effective drugs, like doxycycline, could be substituted. But for doxycycline to work troops had to take the pill daily, without fail. The troops don’t always do that, partly because of the side effects (digestion problems and additional skin sensitivity) and the press of battlefield business.
This sort of thing (troops not taking care of themselves) is not a new problem. In past wars, troops were ordered to do certain things to keep themselves healthy, and commanders faced similar problems with non-compliance. In combat, the troops are stressed and have a lot of things to do, all the time, and often under fire. Lack of sleep creates constant fatigue. So commanders had to accept the additional casualties from troops not using water purification tablets (to avoid drinking water that would make them ill), keeping their feet dry (to prevent skin conditions), wearing their cold weather clothing correctly to avoid frostbite, or drinking enough water in very hot weather to avoid heat related illness, and so on.
Mefloquine only had to be taken once a week, and has been in use since the 1970s. Thus mefloquine was never taken, until recently, by a lot of troops who had experienced many months of combat and developed PTSD.