Everything You Need to Know About Antibiotics

By Chris Bodle, MD
Medically reviewed checkmarkMedically reviewed
June 22, 2021

Antibiotics save lives around the world. Thanks to their ability to effectively treat bacterial infections, lessen their complications, and stop the spread of disease, many consider antibiotics one of modern medicine’s greatest achievements. But the increasing prevalence of antibiotic resistance—coupled with their potentially harmful side effects—means that understanding when and how to take antibiotics is more important than ever. 

In this article, I’ll describe the different types of antibiotics, what they treat, and how to use them. I’ll also explain antibiotic overuse and antibiotic resistance, how to know when antibiotics are or aren’t needed to treat an infection, and possible risk factors and complications. Finally, I’ll cover how to get a prescription to order antibiotics online and when to see a doctor to determine if antibiotics are the right treatment course for you.

What Are Antibiotics?

Antibiotics, also called antibacterials, are a class of powerful medications that eradicate bacteria or slow their growth. It’s been nearly a century since the discovery of the first natural antibiotic, penicillin, which has saved millions of lives. Penicillin-based antibiotics are still in use along with hundreds of others.

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Types of Antibiotics

In addition to penicillin, antibiotics are broadly classified by the following groups:

  • Penicillins: These treat everything from urinary tract infections (UTIs) to skin infections to chest infections.
  • Tetracyclines: Tetracyclines, including doxycycline (Monodox), can be prescribed for common conditions like acne, respiratory infections, and more.
  • Cephalosporins: Antibiotics in this class, such as cephalexin, treat a wide range of infections ranging from strep throat to meningitis and other more serious infections.
  • Macrolides: A common alternative for people who are allergic to penicillin, macrolides such as erythromycin and clarithromycin are ideal for chest and lung infections, STDs, and other infections that penicillin can treat. 
  • Aminoglycosides: Often employed in hospitals, aminoglycosides are typically only used for severe illnesses given their potential for significant side effects. Examples include gentamicin and tobramycin. 
  • Fluoroquinolones: These versatile antibiotics, including ciprofloxacin and levofloxacin, are used to treat a variety of skin, sinus, joint, and urinary infections. However, fluoroquinolones can interact with many common medications.
  • Sulfonamides: Rather than kill bacteria, sulfonamides stop their growth and then lets your immune system do the rest.

Antibiotics also come in a variety of forms, including:

  • Tablets or capsules
  • Liquids
  • Creams or ointments
  • Sprays or drops
  • Injections

What Do Antibiotics Treat?

Antibiotics destroy bacteria and prevent their reproduction. Patients with group A Streptococcus bacteria, for example—bacteria that account for approximately one-third of all sore throats—are often candidates for antibiotics. Sepsis, our bodies’ life-threatening response to extreme cases of infection, is also treated with antibiotics.

Your doctor might prescribe antibiotics for a diverse range of bacterial infections, including:

What Is Antibiotic Overuse?

Antibiotics overuse is the implementation of antibiotics when it’s not the appropriate treatment.

According to the Center for Disease Control and Prevention (CDC), about 30% of antibiotics prescribed in emergency rooms and doctors’ offices around the country are unnecessary.

Patients may request antibiotics hoping to feel better while they wait for test results, despite the fact that, in many instances, antibiotics aren’t needed for their symptoms. Antibiotics are often overused in low-income areas or developing countries due to less sophisticated diagnostic tools and poor sanitation.

The CDC has designated better-informed use and prescription of antibiotics as a national priority for two primary reasons: to keep us healthy in the short-term and to protect the effectiveness of these medications in the future by fighting antibiotic resistance.

What Is Antibiotic Resistance?

Overprescribing antibiotics has resulted in antibiotic resistance, meaning that bacteria have found a way to resist the medication designed to kill it—not that your body has become resistant to antibiotics.

Antibiotic resistance is a growing issue both nationally and internationally, with some bacteria exhibiting resilience to the most powerful antibiotics available.

Every year, over two million people in the U.S. are infected by antibiotic-resistant bacteria, often leading to hospitalizations, or in some cases, death.

When Are Antibiotics Needed?

Antibiotics should only be used to treat certain bacterial infections. Strong antibiotics are vital if you’ve been diagnosed with serious illnesses like pneumonia and sepsis, or if you’re at a higher risk of infection, including if you’re having surgery or receiving chemotherapy.

To avoid contributing to antibiotic resistance, here are some principles I recommend to practice antibiotic stewardship:

  • Maintain good hygiene to protect yourself against bacterial infections
  • Make sure you and your family are up to date on immunizations
  • Lessen your risk of foodborne bacterial infections by washing your hands and cooking foods to the proper temperature
  • Only use antibiotics prescribed by your doctor, and only use them in the way your doctor recommends

Why you should continue taking antibiotics even if you feel better

If a doctor prescribes antibiotics and you begin to feel better, you should still complete the course of treatment as recommended by your doctor. Bacteria may still live in your body, and if you stop antibiotics early, they can begin to grow again and spread. This can cause more severe infections or new infections, lengthening your recovery time.

When Are Antibiotics Not Needed?

Two main types of germs produce illnesses in humans: bacteria and viruses. Because bacteria are living organisms, antibiotics are able to stop their reproduction and growth.

Viruses replicate differently. Instead of attacking your body like bacteria do, they attach themselves to your healthy cells, using those cells to multiply the virus through your body. Because of that, antibiotics are ineffective in killing viral infections. In many cases like the common cold, you have to wait for viral infections to run their course.

Taking an antibiotic for a viral infection will not cure the infection, make you feel better, or protect others from contracting it. Instead, it will also promote antibiotic resistance. Viral infections that aren’t improved by antibiotics include:

How to Get an Antibiotic Prescription

In the United States, antibiotics are only available via prescription, so you need to speak to a medical professional to obtain them. The provider will ask about your symptoms and medical history and may run additional tests to determine which antibiotic, if any, is right for you.

Can You Get Antibiotics Online?

You can speak with a medical practitioner online through many available and secure telehealth platforms—including the K Health app—to discuss your symptoms and, if applicable, get a prescription for antibiotic medication.

Once you have a prescription, you can order antibiotics from licensed online pharmacies or pick up your prescription at your local pharmacy.

Risk Factors and Complications of Antibiotics

Whenever you start a new medication, it’s important to talk to your healthcare provider about any known allergies, medical conditions, and other medications you take, as some antibiotics may not be suitable for everyone.

The most common side effects of antibiotics include:

Allergic reactions to antibiotics occur in approximately one in 15 people, causing symptoms ranging from skin rashes and itching to difficulty breathing. Another side effect of antibiotics can be development of Clostridioides difficile infection (referred to as C. diff or C. difficile). C. diff causes severe diarrhea, leading to colon issues and potentially life-threatening complications.

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Can you drink alcohol while taking antibiotics?

Most common antibiotics are not likely to cause problems when combined with moderate alcohol consumption. However, two types of antibiotics can produce serious reactions when combined with alcohol: metronidazole and tinidazole. Both can be used to treat some vaginal infections, dental infections, and chronic skin sores among other things.

You should avoid alcohol while taking these medications, otherwise side effects could include dizziness, hot flashes, headaches, and irregular heartbeat. Other antibiotics that could produce side effects, though to a lesser extent, include doxycycline and linezolid.

Avoiding alcohol when you’re feeling unwell is generally a safe practice, as alcohol consumption can make you feel worse. Consult your doctor or chat with a K physician about drinking alcohol if you’re prescribed an antibiotic.

Can you take antibiotics while on birth control?

Though previous research was mixed, a study published in the Journal of the American Academy of Dermatology concluded that taking birth control pills with many commonly prescribed antibiotics, including ciprofloxacin (cipro), doxycycline, and clarithromycin, does not affect hormone levels or oral contraceptive efficacy. 

Only one antibiotic, rifampin, has been shown to reduce plasma estrogen concentrations to make birth control pills, vaginal rings, and birth control patches less effective. 

Regardless, let your doctor know if you use hormonal contraception before being prescribed an antibiotic.

When to See a Doctor

If you have signs or symptoms of a bacterial infection, talk to your doctor about whether an antibiotic prescription is right for you. The sooner you receive the appropriate treatment, the sooner you can remedy your symptoms and prevent more severe infections.

How K Health Can Help 

Did you know you can get affordable virtual care with the K Health app? Download K to check your symptoms, explore conditions and treatments, and if needed text with a doctor in minutes for just $35.

K Health articles are all written and reviewed by MDs, PhDs, NPs, or PharmDs and are for informational purposes only. This information does not constitute and should not be relied on for professional medical advice. Always talk to your doctor about the risks and benefits of any treatment.

Chris Bodle, MD

Dr. Bodle is a board certified emergency medicine physician. He received his medical degree from Indiana University School of Medicine, and completed his residency in emergency medicine at Emory University. In addition to K Health, he currently works as an Emergency Medicine physician in an Urban, Level 1 Trauma Center in the south east.