What is the Difference Between Antibiotics and Antivirals?

Antibiotics are used to treat bacterial infections such as urinary tract infections (UTIs), pneumonia, sinus and ear infections, and strep throat. While most antivirals work by stopping a virus from entering healthy cells or by inhibiting viral DNA replication. Unlike antibiotics, antivirals mostly inhibit the growth and replication of viruses as opposed to killing the pathogen.

Sophie Wei

Sophie is a 2024 Pharm D. candidate studying pharmacy at Rutgers University, New Brunswick. She has a passion for healthcare and writing and hopes to make meaningful contributions to healthcare transparency and accessibility. In her free time, she likes to take care of her houseplants, cook, and hang out with her cat.

Antibiotics and Antivirals are both used to treat infectious diseases. However, antibiotics are used to treat bacterial infections whereas antivirals are used to treat viral infections. Your physician will prescribe you an antiviral or an antibiotic depending on if you have a bacterial or viral infection. These medications also differ in side effects and cost.

What are Antibiotics?

Antibiotics are medications used to treat bacterial infections. How each antibiotic works is a little bit different, but in general, antibiotics inhibit cell wall formation, prevent bacterial DNA formation, and halt bacterial protein formation.

Common Antibiotics

Antibiotics are used to treat bacterial infections such as urinary tract infections (UTIs), pneumonia, sinus and ear infections, and strep throat. There are several classes of antibiotics, all with varying levels of efficacy against different strains of bacteria. Each medication also has a range of possible adverse effects. Below are some common antibiotics..

Common Antibiotics and What They Treat

Note: the listed medications are not the only ones available in each class. Additionally, several of these medications can be used for a wide variety of diseases - the treatments listed above are not comprehensive. The cost of antibiotics listed in the chart is based on GoodRx pricing and is a good estimate of your general costs without insurance coverage.

Side Effects of Antibiotics

The most common side effects of antibiotics include gastrointestinal issues. These effects include:

• Feelings of nausea
• Loss of appetite
• Diarrhea
• Bloating
• Abdominal pain

However, most of these side effects tend to be mild. In order to help curb some of these effects, you can take probiotics to help supplement the “good bacteria” in your gut and prevent nausea.

Some individuals can also have allergic reactions to certain antibiotics (penicillins, cephalosporins) that can range from mild to severe. Mild and moderate reactions include skin rashes or hives accompanied by coughing. These symptoms can be treated with over-the-counter antihistamines such as cetirizine or with topical steroids such as hydrocortisone cream.

For instance, tetracyclines can make your skin more sensitive to light and can also cause bone and tooth discoloration. Some antibiotics such as vancomycin can also lead to kidney toxicity. More severe side effects of antibiotics include anaphylaxis which is a severe and potentially fatal allergic reaction that leads to difficulty breathing, confusion, and loss of consciousness. Be sure to ask your doctor about potential side effects and the best ways to treat them when prescribed an antibiotic.

What are Antivirals?

Antivirals are a class of medications used to treat viral infections. Antivirals are grouped into different subclasses based on how they work. Most antivirals work by stopping a virus from entering healthy cells or by inhibiting viral DNA replication. Unlike antibiotics, antivirals mostly inhibit the growth and replication of viruses as opposed to killing the pathogen.

Common Antivirals

Antivirals are used to treat viral infections including but not limited to the flu, herpes viruses, and COVID-19. Common antivirals include:

• Oseltamivir, also known as Tamiflu: used for symptoms caused by the flu (influenza virus)
• Peramivir, also known as Rapivab: used for symptoms caused by the flu (influenza virus)
• Penciclovir, also known as Denavir: used for cold sores caused by the herpes virus
• Bictegravir/Emtricitabine/Tenofovir Alafenamide, also known as Bictarvy: is used to treat HIV/AIDs
• Remdesivir, Veklury: used to treat COVID-19 infection
• Nirmatrelvir/ritonavir, Paxlovid: used to treat COVID-19 infection
• Acyclovir, also known as Stiavig or Zoviraz: used for herpes sores and can treat shingles or genital herpes

It is important to note that several viral infections can be prevented with vaccination instead of antiviral treatment. These infections include chickenpox (VZV virus), measles, mumps, and rubella. Make sure that your vaccinations are up to date in order to prevent these viruses.

Cost of Common Antivirals

Antivirals tend to cost more than antibiotics since they tend to be more difficult to manufacture. Depending on your disease state and insurance status, the cost of an antiviral medication might differ from the chart below. The chart below provides an idea of the cost of commonly prescribed antivirals without insurance.

Cost of Common Antivirals Without Insurance

Side Effects of Antivirals

Side effects of antivirals can differ based on the class of medication, however, there are general class-wide side effects to be aware of. Antivirals can cause gastrointestinal-related effects including:

• Nausea
• Vomiting
• Diarrhea

Long-term use of antivirals can lead to kidney problems. Other less common side effects include mental disturbances such as depression, anxiety, or agitation.

Antivirals and Antibiotics Frequently Asked Questions (FAQs)

The following section can help clarify some common questions about antibiotics and antivirals.

Can I get antibiotics and antivirals over the counter?

Most antibiotics are not available over the counter, however, there are some exceptions for topical antibiotics. These include antibiotics that can help to treat mild cuts or burns such as Neosporin or Polysporin.

Under federal law, antivirals are not available over the counter. This means that in order to obtain these medications, you need a valid prescription from a health care provider.

Does antiviral resistance exist?

Like bacteria, viruses have also been documented to have resistance to antiviral medications. This means that certain viruses are not susceptible to commonly used antiviral agents due to mutations of the virus itself. These diseases include AIDs, hepatitis B, and influenza among others. Antiviral resistance has the potential to be a large public health risk and is important to be aware of.

What is the difference between antivirals and vaccination?

Vaccines are different from antivirals in that they prevent infections before they occur. They are designed to trigger an immune response in the body prior to exposure to the virus. When you are exposed to the virus, your body can mount a robust immune response and prevent illness. Antivirals, on the other hand, treat individuals who have already been infected by killing the virus or by preventing the growth of the virus.

Bottom Line

Ultimately, both antibiotics and antivirals are commonly used medications that are essential for treating infectious diseases. However, they differ in a lot of ways and have their own specific classes, side effects, and uses. Additionally, the cost of these medications varies drastically depending on what illness you are treating, but common antivirals tend to cost more than common antibiotics.

You generally need a prescription in order to obtain both antibiotics and antivirals.