One of the things that has recently complicated my life has been a prescription for Levofloxacin. Levofloxacin is a member of the Fluoroquinolones family of drugs. They're excellent at killing bacteria, but they carry very serious and dangerous side effects. Two of the worst side effects are damage to the aorta and Achilles tendon rupture. There has been a black box warning for the Achilles since 2008. There's a long list of other bad things, but those are the two most significant. The risk of damage increases with the age of the patient. If you are over 60, your risk is increased.
Doctors like to prescribe these drugs because they work quickly on the bacteria (such as pneumonia) and then the patient feels better. However, they're over prescribed. My doctor did not say one word to me about the risks of this drug. I was already aware from reading doctor blogs and discussing it with a couple of other docs I see, so I decided to take the risk because I was so sick. It was a bad decision. Four days after starting a low dose of Levofloxacin, the backs of my legs were giving me agony if I stood still for more than 60 seconds. Walking is OK, standing is not. I took 6 of the 7 pills and quit early, deciding I'd rather risk a super bug than hurt my legs anymore. There is a lot of literature about these drugs on the internet, on reputable sites.
Here is one source, and there is another below, linked in the title.