How to Be Safe With Antibiotics

By Rosanna Sutherby, PharmD

November 13, 2020

Antibiotic Resistance

The use of modern-day antibiotics began with the discovery of penicillin by Alexander Fleming in 1928 and its mass distribution in the 1940s. These drugs have been curing infections and saving lives since then, but using them safely and appropriately helps ensure that they will continue to be effective for years to come.

What Are Antibiotics?

Antibiotics are medications used to treat infections caused by bacteria. They work by killing the bacterial cells or by preventing them from growing or multiplying.

What Conditions Do Antibiotics Treat?

Antibiotics treat infections caused by bacteria.

Examples of conditions that antibiotics treat include:

  • Pneumonia
  • Sepsis (when an infection spreads to other parts of your body)
  • Some skin infections
  • Strep throat
  • Stomach ulcers caused by the bacteria Helicobacter pylori
  • Tuberculosis
  • Urinary tract infections (UTIs)

Antibiotics do not work against infections caused by viruses or fungi, such as:

  • Bronchitis
  • Common cold
  • Flu
  • Ringworm
  • Yeast infections

What Is the Best Way to Take Antibiotics?

Always take your antibiotics according to the directions on your medication label. You should take antibiotics at regular time intervals and for the entire duration of your treatment, even if you're feeling better. Stopping your antibiotic before the number of days your doctor prescribed can cause your infection to return or lead to antibiotic-resistant bacteria.

It is important that you use your antibiotics only for the condition that your provider prescribed. Many antibiotics are active against specific bacteria and may not work for other conditions. Do not use leftover antibiotics from a previous infection, and do not share your medication with others.

Antibiotics are designed to kill bacteria based on the amount of time they take to reproduce and how long the medication is active in your body. Therefore, different antibiotics have different instructions on how often to take them. Waiting too long between antibiotic doses increases the chance of bacteria growing and becoming resistant to the medicine.

The following are examples of appropriate time intervals for taking your antibiotics. If your label says to use the medicine:

  • Twice a day – take your dose every 12 hours
  • Three times a day – take your dose every 8 hours
  • Four times a day – take your dose every 6 hours
  • Six times a day – take your dose every 4 hours

Depending on what time of the day you begin taking your antibiotics, you may not be able to get all your doses in on your first day – and that's OK. Take as many doses as you can on the first day and plan the remaining days of your therapy so that you can fit in all your doses at the correct time intervals.

Should You Take Antibiotics With Food?

Taking antibiotics with food helps minimize side effects such as nausea and diarrhea. However, some antibiotics have special considerations when it comes to food:

  • Azithromycin (Zithromax, Z-Pack): Taking azithromycin with food decreases its availability by up to 43%. If you can tolerate it, take azithromycin on an empty stomach to get the medicine's best effect.
  • Fluoroquinolones: Fluoroquinolone antibiotics include ciprofloxacin (Cipro), levofloxacin (Levaquin), and others. These antibiotics can bind to minerals, such as calcium, iron, and magnesium, which decreases their absorption. Avoid foods, drinks, antacids, or vitamins that contain these metal ions. Additionally, many fruit juices reduce the absorption of ciprofloxacin. It is safest to take fluoroquinolone antibiotics with water.
  • Tetracycline: Take tetracycline one hour before or two hours after a meal. Avoid foods, antacids, or vitamins that contain calcium or other cations, such as magnesium or iron.

What Is Antibiotic Resistance?

Antibiotic resistance happens when bacteria find ways to fight the antibiotics that are designed to kill them. When bacteria become resistant to antibiotics, they can grow and reproduce even if you are taking an antibiotic. Antibiotic resistance is dangerous because it is difficult or sometimes even impossible to treat resistant bacteria with the medicines that are available.

To prevent antibiotic resistance:

  • Take your antibiotics exactly as your doctor prescribed them.
  • Do not share your antibiotics.
  • Do not save antibiotics for a later time.
  • Do not take someone else's antibiotics.
  • Finish the entire course of your antibiotic therapy, even if you feel better.
  • Do not take antibiotics when they are not necessary.

Do Antibiotics Interact With Birth Control Pills?

Some antibiotics, including rifampin, amoxicillin, and Augmentin (amoxicillin/clavulanic acid), may decrease the effects of your birth control pills. Be sure to talk to your pharmacist or prescriber about antibiotic drug interactions. If your antibiotic interacts with your oral contraceptive, be sure to use an alternative method of birth control while taking these antibiotics. You can continue taking your birth control pills while using a barrier method of contraception, such as a condom or diaphragm.

Do Antibiotics Interact With Heart Medication?

Fluoroquinolone antibiotics may interact with some medications, including heart medicine, and increase your risk of heart arrhythmias (irregular heartbeat).

Examples of medications that may increase your risk for heart arrhythmias if taken with fluoroquinolones include:

It is crucial to let your healthcare provider know all the medicines you take and your medical history when you are being prescribed an antibiotic.

Antibiotics are life-saving drugs when used safely and correctly. Remember, antibiotics do not treat all infections, and individual antibiotics can only kill the range of bacteria they cover. Following your healthcare provider's instructions for taking your antibiotics helps to get the best effects from your medication and prevents the growth of dangerous antibiotic-resistant bacteria.

Rosanna Sutherby is a freelance medical writer who has been a practicing pharmacist in her community for close to 20 years. She obtained her Doctor of Pharmacy from Nova Southeastern University in Ft. Lauderdale, FL. She utilizes her clinical training in the pharmacy, where she helps patients manage disease states such as asthma, diabetes, heart disease, hypertension, and many others. Dr. Sutherby reviews and recommends drug regimens based on patients’ concurrent conditions and potential drug interactions.


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