Most people don't know how to adjust a timing belt and they don't have the equipment to do so. Just about anyone can walk into a Farmacia here and ask a primary school dropout what they should be taking for syphilis. Self medicating is kinda like working on your car; If you screw it up you can ruin the engine.
If one understands the types of antibiotics available and which will best address a particular infection, with some careful research they can make an informed decision as to which one. The how much for how long requires access to the manufacture's dosing instructions which are usually only provided directly to physicians or in a pharmacology reference book such as a PDR which is sometimes difficult to understand by the lay person. There are in a lot of instances hurdles put in place by manufacturers to prevent non-doctors from getting easy access to clinical product info and what is easily searchable online may not be the most accurate guidance available.
But hey, feel bad, take a pill... I'm particularly fond of the green ones.
To bring this back to the OP, yeah some people die after taking boner pills, having mixed in some alcohol and some other unrelated medications for good measure. This happens because pills can be had just for buying gasoline apparently. Short term antibiotic use usually won't kill you but it can make your condition worse rather than better if you get the drug/dosage wrong.
There are risks associated with boner pills beyond the common "if you have a woody for more than 3 hours see a doctor" suggestion. Viagra was originally developed to reduce fluid buildup in tissues such as the pericardium, low and behold an off script side effect is well, we all know. These pills can present a real danger to someone already taking high blood pressure medication but to know this you would have to read the package insert which I am sure they don't hand out at the gas station or the farmacia is you are buying fewer than a whole box at a time.