Antibiotics: Uses, Side Effects, Overuse & Buying Online

By Terez Malka, MD
Medically reviewed checkmarkMedically reviewed
June 3, 2022

Antibiotics save lives all over 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. 

However, the increasing prevalence of antibiotic resistance—coupled with their potentially harmful side effects— shows that it is very important to use antibiotics only when they are really needed and to avoid  self-medication.

It also shows that understanding when and how to take antibiotics is more important now than ever. 

This article will describe the different types of antibiotics, what they treat, and how to use them.

It will also explain antibiotic use, 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, It will cover how to get a prescription to order antibiotics online and when to see a doctor or healthcare provider to determine if antibiotics are the right treatment course for you.

What Are Antibiotics?

The term “antibiotic” is used for an antimicrobial agent that targets bacteria.

Antibiotics, also called antibacterials, are a class of powerful medications that destroy bacteria or slow their growth. 

There are many different antibiotics on the market today for treating both severe and mild bacterial infections. It’s been nearly a century since the discovery of the first antibiotic, penicillin.

The discovery of penicillin has saved millions of lives. In recent years, penicillin-based antibiotics are still in use along with hundreds of others.

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Types of Antibiotics

Penicillin is one class of antibiotics, but there are may others.

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 are prescribed for conditions like acne, respiratory infections, and more.
  • Cephalosporins: Antibiotics in this class, such as cephalexin, treat a wide range of infections ranging from skin infections  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 used 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 and can cause severe side effects.
  • Sulfonamides: Rather than kill bacteria, sulfonamides stop their growth and then let your immune system do the rest. One commonly used sulfonamide, trimethoprim-sulfamethoxazole (Bactrim), is typically used for UTIs and skin infections.

These all act to treat bacterial infections in different ways, e.g., by attacking bacterial cell walls, inhibiting the synthesis of their proteins, or stopping the growth of bacteria. 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 offer effective treatments for bacterial infections.

They destroy bacteria and prevent their reproduction.

Patients with group A Streptococcus bacteria, for example—bacteria that account for approximately 15% 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 or provider might prescribe antibiotics for a diverse range of bacterial infections, including:

People who are prepping for surgery may also be administered antibiotic prophylaxis to prevent a bacterial infection.

Topical antibiotics available as drops, ointment, or cream, can be used for many skin, eye, and outer ear infections.

Antibiotics are not effective for treating illnesses caused by viruses, e.g., colds and flu

Most common febrile illness, sinus infections, and respiratory infections are caused by viruses and antibiotics will not help.

What Is Antibiotic Overuse?

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

This can have many bad effects including unnecessary side effects, allergic reactions, an imbalance of healthy gut and vaginal bacteria, diarrhea, and yeast infections.

It can also put you at risk for more severe infections.

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

Antibiotic misuse may also involve using more than the prescribed dose of your antibiotics, using an old antibiotic that was prescribed for something else or someone else, or not completing the full course you were prescribed.

Patients may request antibiotics hoping to feel better while they wait for test results.

In most cases, antibiotics should only be started once your provider is sure there is a bacterial infection that they are needed for.

Overuse of antibiotics is common in low-income areas or developing countries due to less sophisticated diagnostic tools, misinformation, and the availability of antibiotics over-the-counter in some countries.

The CDC has designated better-informed use and prescription of antibiotics as a national priority for two primary reasons: to keep the general public 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 them—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.

The World Health Organization has made it a priority to tackle this issue of antimicrobial resistance.

The best way to prevent rising antibiotic resistance is to take antibiotics only when truly needed, and when prescribed for you, and to take your antibiotic exactly as prescribed.  

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 bacterial infections or illnesses like pneumonia and sepsis, or if you’re at a higher risk of infection, including if you’re having surgery or receiving chemotherapy.

Your healthcare provider will prescribe medicine for you depending on the strain of bacteria that infected, your medical history, and your specific infection and symptoms.

To avoid contributing to antibiotic resistance, here are some principles healthcare experts recommend to practice responsible antibiotic use:

  • Maintain good hand 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
  • Seek medical advice if you experience symptoms of illness
  • Only use antibiotics prescribed by your provider, and always use them exactly as prescribed

Why you should continue taking antibiotics even if you feel better

If a healthcare provider prescribes antibiotics and you begin to feel better, you should still complete the course of treatment.

This is not considered inappropriate use of antibiotics because bacteria may still live in your body, and if you stop antibiotics early, it can cause drug resistance (the bacteria 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 healthy human 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, COVID, the flu, and most coughs and sinus infections, you have to wait for viral infections to run their entire course and antibiotics will not help.

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 the spread of resistance among even otherwise healthy people.

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. 

The good news is that K Health can help you get the best treatment by connecting you with a healthcare professional right away. 

Can You Get Antibiotics Online?

You can speak with health professionals online through many available and secure telehealth platforms—including the K Health app—to discuss your symptoms and, if applicable, get a prescription for an 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, severe side effects, medical conditions, and other drugs you take, as some antibiotics may not be suitable for everyone.

The most common side effects of antibiotics include:

Antibiotics can cause serious side effects such as allergic reactions.

This occurs in approximately one in 15 people, causing symptoms ranging from skin rashes and itching to difficulty breathing. 

Another serious side effect of antibiotics can be the development of Clostridium difficile infection (referred to as C. diff or C. difficile). C. diff causes severe diarrhea, leading to colon issues and potentially life-threatening complications.

While this is a rare complication, it is one reason why it is important to use antibiotics only when needed.

If you experience severe diarrhea within a few weeks or months after taking an antibiotic, let your healthcare provider know right away.

Can you drink alcohol while taking antibiotics?

Most common antibiotics are not likely to cause problems when combined with moderate alcohol consumption. However, medical advice often recommends avoiding alcohol while taking antibiotics

Two types of antibiotics can produce serious reactions when combined with alcohol: metronidazole and tinidazole. Both are used to treat vaginal infections and intraabdominal infections.

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, can prolong your infection, and can increase your risk of side effects.

Consult your provider or chat with a K provider if you have questions about drinking alcohol if you’re prescribed an antibiotic.

Can you take antibiotics while on birth control?

A study published in the Journal of the American Academy of Dermatology concluded that taking birth control pills with many commonly prescribed antibiotics 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, you should give your doctor or provider all the relevant information necessary to give you the right treatment. Let your provider know if you use hormonal contraception before being prescribed an antibiotic.

They will let you know if a different antibiotic is preferred, or if you should use a backup birth control method while on the medication.

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When to See a Doctor or Medical Provider

It is best to avoid taking prescription medications on your own anytime you feel sick.

If you have signs or symptoms of a bacterial infection, talk to your health care provider about whether an antibiotic prescription is right for you.

If you are allergic to a particular antibiotic, you should also inform your provider to avoid a serious allergic reaction to your medication. 

Your healthcare provider will have to diagnose you first.

This may be done by listening to your symptoms and performing a physical exam, and in some cases, labs or imaging tests are needed.

You may be given intravenous or oral antibiotics depending on the type or severity of your infection.

If you do not have signs of a bacterial infection, your provider can help suggest other treatments.

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 or licensed provider 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.

Terez Malka, MD

Dr. Terez Malka is a board-certified pediatrician and emergency medicine physician.