What happens if you don’t finish antibiotics?

In this article:

• How do antibiotics work?
• Duration of antibiotics
• What happens if you don’t finish antibiotics?
• What happens if you miss a dose?
• Bottom line

In this article

• How do antibiotics work?
• Duration of antibiotics
• What happens if you don’t finish antibiotics?
• What happens if you miss a dose?
• Bottom line

Your healthcare provider prescribed you a 10-day course of antibiotics for that nasty case of bronchitis, but you’re feeling better after five days. Do you still have to keep taking your prescription? Isn’t it better to not take medication you don’t really need?

Well, yes…and no! Antibiotics are powerful drugs designed to kill infectious diseases caused by bacteria—think strep throat, ear infections, and urinary tract infections, among others—but they’re no good in the fight against common infections caused by viral illnesses. Taking an antibiotic when you have a virus like the common cold or flu won’t help you, and worse, it can actually do some harm.

“Taking antibiotics for a cold [is one of the things] that causes antibiotic resistance,” says Natalie Long, MD, a University of Missouri Health Care family practitioner. “When you do that, all the non-harmful bacteria in your body are exposed to the antibiotic and can adapt or evolve, making it harder for them to be killed by that antibiotic in the future.”

That said, if you’ve got a bacterial infection, you probably need an antibiotic to get rid of it—and yes, you need to take every single pill, regardless of how quickly you start feeling better. Here’s why.

How do antibiotics work?

There are two types of antibiotics: bacteriostatic and bactericidal, according to Gwen Egloff-Du, Pharm.D., at Summit Medical Group in New Jersey. Bacteriostatic antibiotics, like azithromycin and doxycycline, stop bacterial growth. Bactericidal antibiotics, like amoxicillin and cephalexin, kill the bacteria itself.

When you show up sick at your healthcare provider’s office, they assess your symptom history to determine if your illness is viral or bacterial. If you have a bacterial infection requiring the use of antibiotics, says Long, they will consider the organ system affected. Different parts of the body harbor various types of bacteria common to that location, so healthcare providers prescribe antibiotics that have a good chance of being effective there (i.e., ear infections are caused by different bacteria than UTIs, and will likely require a different kind of antibiotic).

Additionally, the severity of the infection helps determine the length of your treatment, with less severe illnesses typically requiring a shorter course of antibiotics than more serious infections.

How does your healthcare provider determine the duration of antibiotics?

Sometimes you take an antibiotic for five days, but sometimes it’s 14. What gives?

Dr. Long says that treatments vary based on several factors, and physicians and researchers continually revisit the duration of antibiotic treatment.

“Some infections are clear cut, like ear infections, and the duration is pretty standardized,” she explains. “Others, like UTIs, have a range of anywhere from three to 14 days based on how sick you are, whether you need to be admitted to the hospital, and how quickly you respond to the drug.” Other important determining factors are the antibiotic used to treat the infection and other chronic conditions you may have, such as asthma, diabetes, or heart disease, which may require longer courses of antibiotics.

What happens if you don’t finish antibiotics?

There are two reasons why you need to take the full prescribed treatment of antibiotics, Dr. Egloff-Du says. The first is obvious: Your healthcare provider selected the therapy for a reason, and that’s to get you healthy again. The second reason? The dreaded antibiotic resistance we mentioned earlier.

“By completing your course of treatment, you increase the odds of killing all the bacteria responsible for causing your current illness,” explains Dr. Egloff-Du. “When you halt treatment early, you allow a small portion of bacteria to remain in your body, and that bacteria has the potential to strengthen, change, and develop resistance.” This increases the risk of resistant infections from antibiotic-resistant bacteria, referred to as “superbugs” by health professionals.

So, even if you’re feeling better after a few days, that doesn’t mean all of the bacteria that made you sick is actually gone. Per the Centers for Disease Control and Prevention (CDC), antibiotic resistance is a major public health threat that affects upward of 2.8 million people every year. Antimicrobial stewardship, a practice enforced by various healthcare professionals, helps ensure that the right antibiotic is prescribed at the right dose and for the correct amount of time to maximize patient outcomes and minimize the development of antibiotic resistance. 

What happens if you miss a dose of antibiotics?

Look, we’ve all been there—when you’re supposed to do something twice a day for two weeks, it’s not hard to forget about it at least once. In fact, it’s so common that Dr. Long says she actually considers this when she prescribes common antibiotics to patients (because it’s easier to remember one pill a day versus four!).

So what should you do if you miss a dose of antibiotics? That depends on how long it takes you to realize your mistake. “If you are a few hours late in taking your antibiotic, take it as soon as you remember,” advises Dr. Egloff-Du. “But if your next dose is due soon, do not double up.”

The general rule is that if you are more than 50% of the way toward your next dose, you should skip it. So, for example, if you are supposed to take your antibiotic every 12 hours, you could take it if you are less than six hours away from your next scheduled dose.

Instead, take the next dose when it’s due, understanding that your therapy may need to be extended to incorporate the dose you missed. (If you’re not sure what to do, remember that you can always ask your primary care provider or pharmacist for assistance.) For people who struggle to remember their medication, Dr. Egloff-Du offers a few helpful tips.

“Many patients find pillboxes helpful, and others set alarms on their cellphones,” she says. “Combining [your dose] with one of your daily routines, like taking it when you eat breakfast at 8 a.m. every morning, can also be helpful.”

RELATED: The best pill reminder smartphone apps

If you miss several doses or days of antibiotics for any reason, Dr. Egloff-Du adds, it’s important to talk to your healthcare provider; likewise, if unpleasant side effects are deterring you from taking your antibiotic prescription, you should also pick up the phone—your healthcare provider may be able to suggest an alternative therapy.

Bottom line

Even if you start to feel better before finishing the medication, completing the full course of antibiotics is crucial. That’s because stopping antibiotics early can lead to incomplete treatment and increase the risk of antibiotic resistance, making future infections harder to treat. Your best bet? Follow your healthcare provider’s instructions, consulting them for guidance if you’re unsure about missed doses or side effects. Adherence to your prescribed antibiotic regimen helps ensure effective recovery and protects public health.