TORONTO — Most of us have heard the cardinal rules of antibiotics.
Don’t take them when they aren’t needed. And when they are prescribed, take every last pill — do not stop just because you start to feel better.
There are other rules, however, that many of us may not know. And some myths that we think are true but are not.
The missing information and the misconceptions can keep you from taking antibiotics appropriately, meaning you may not get the maximum benefit and may put yourself at risk of developing a drug-resistant infection in the process.
Taking the pills correctly may be at least as important as taking all of the pills in your prescription, experts say.
Interactions with foods, other drugs and even supplements like multivitamins can interfere with the body’s ability to absorb antibiotics. The consequence? You end up getting a lower dose than you need to kill those germs.
“If it isn’t being absorbed, for whatever reason . . . then it’s not going to get to the site of infection at adequate levels to appropriately treat the infection,” Dr. Andrew Simor, chief microbiologist at Toronto’s Sunnybrook Health Sciences Centre, explains.
“And you run the risk of not responding to treatment or of having sub-therapeutic levels of an antibiotic that can promote resistance.”
But taking antibiotics properly can be tough, especially if you are prescribed one of the older types. Some newer antibiotics use a one-pill-a-day regimen, but older types may require you to pop three or four pills a day — on an empty stomach.
Remembering to take them an hour before eating or a couple of hours after eating can be difficult. But forgetting and taking them on even a semi-full stomach can mean your body only absorbs a half or a quarter of the active ingredient in the drug, says Clarence Chant, a pharmacist at St. Michael’s Hospital in Toronto who works in the intensive care unit and specializes in infectious diseases.
Under those circumstances, you are essentially under-dosing yourself. And that can give rise to antibiotic resistance.
That’s because when you have a bacterial infection, you aren’t harbouring a single bug, but a swarm of a type of bug — whether that’s Strep or Staph or some other bacterium. If you are infected with bacteria that are susceptible to antibiotics, most members of that hoard will be vulnerable to the drug.
But there can be a few in the crowd that have mutations that let them fight off the antibiotic if the level of the drug in your system is too low. If you are getting a sub-optimal dose because you are taking your antibiotics incorrectly, you could end up killing off only the weaker bacteria. The result: The resistant ones survive and thrive.
“That’s why the instructions of how to take an antibiotic are just as important as ensuring you take it for the right duration,” Simor says. Ideally, antibiotics that are taken three or four times a day should be spaced out evenly, he says. With the ones that need to be taken on an empty stomach, you could find yourself needing to wake up in the night to get all the pills down over a 24-hour period.
But not all antibiotics have to be taken on an empty stomach. The macrolide class of antibiotics — erythromycin is an example — can trigger nausea when taken on an empty stomach. So for them, the recommendation is to take the pills with food.
The range of types of antibiotics and the different ways they are meant to be taken mean you really need to get clear instructions from your doctor and your pharmacist on how to correctly take your meds. Don’t assume the antibiotic for the infection in your chest is taken the same way as the antibiotic you took for that urinary tract infection a couple of years ago.
“The most important thing, I guess, is have a dialogue with the pharmacist when you’re getting a prescription,” says Chant.
Make sure that talk includes a discussion about the other drugs, vitamins and herbal supplements you are taking. They can interact with antibiotics as well.
For instance, an older type of antibiotic called the tetracyclines binds to calcium. That means you don’t want to take them with milk or dairy products. But multivitamins can contain calcium too, so if that is the kind of antibiotic you are taking, you don’t want to take your pills around the time you take your multivitamin, Chant says.
Iron supplements could interfere with absorption of this type of antibiotic as well, he says.
However, something a lot of people believe will interact negatively with antibiotics — alcohol — actually doesn’t in most cases, Simor and Chant say. Alcohol in moderation won’t affect uptake of the active ingredient of most antibiotics.
“It’s probably not a good idea to drink alcohol when you’re sick with an infection, but that’s a different story,” Chant says.
There are exceptions. Metronidazole (sold as Flagyl) can induce severe nausea when a person taking it drinks alcohol. “It varies from drug to drug. But many antibiotics can be taken with small or modest amounts of alcohol,” Simor says.
Just as you need to make sure other medications or supplements don’t interact negatively with antibiotics, you should ask if your antibiotics will have a negative impact on any other drugs you might be taking. And that includes oral contraceptives.
There are differing views on whether antibiotics interfere with absorption of contraceptives. But Chant thinks there might be something to the notion.
“My opinion would be that definitely from ... understanding how the antibiotics are handled in your body as well as the oral contraceptives, that there’s definitely some truth to it,” he says.
“I don’t know how well studied it is. ... (But) the interaction is probably there. It makes sense pharmacologically speaking.”
The complexity of the possible interactions means there are plenty of chances for things to go awry. If you go to one physician for all your care and see one pharmacist for all your prescriptions, that could minimize the chances of interactions or missteps.
But the reality is that isn’t always possible.
And that means people getting prescriptions for antibiotics need to be their own advocates — making sure they inform the prescribing doctor and the pharmacist of the other drugs and supplements they are taking to maximize the potential for benefit and minimize the risk of adverse interactions.
“For all aspects of health care, you can’t just delegate responsibility to any one health-care provider,” Simor says. “It’s got to be a joint effort — a partnership, if you like, between the patient and health-care providers. And yes, the patient has to take ownership as well.