Here’s Why Antibiotics Don’t Work for the Flu

Many people are tempted to take an antibiotic when they get sick. After all, antibiotics can quickly treat many infections. But different kinds of infections need different treatments. And the flu (influenza) is one of the infections that antibiotics don’t treat.

What kind of infection is the flu?

The flu is a viral infection. The germ that causes it — the influenza virus — is very small. Like all viruses, the influenza virus is not technically alive. It’s more like a tiny machine that sticks to surfaces and hovers in the air inside water droplets. 

The influenza virus spreads easily from person to person. When it gets inside your mouth, nose, or eyes, it attaches to your healthy cells. It takes control of those healthy cells and uses them to multiply itself and cause an infection.

Here are some other viral infections you might recognize:

• COVID-19

• Common cold

• Herpes

• HIV

• Chickenpox

• Shingles 

Why don’t antibiotics work against viruses?

Antibiotics fight bacteria. Bacteria are different from viruses. Bacteria are living cells that can multiply on their own and form colonies. 

Some antibiotics work by killing bacteria directly. Others work because they stop bacteria from multiplying. Either way, those strategies don’t work on viruses. 

Do antibiotics treat flu infections?

No. Antibiotics are designed to kill bacteria, so they don’t work for viruses like the flu. Bacterial infections that can be treated with antibiotics include: 

• Strep throat

• Whooping cough

• Tuberculosis

• Urinary tract infection (UTI)

• Bacterial pneumonia

If you need to treat a bacterial infection, your healthcare provider might prescribe antibiotics such as:

• Amoxicillin with clavulanate (Augmentin)

• Cephalexin (Keflex)

• Sulfamethoxazole with trimethoprim (Bactrim)

• Metronidazole (Flagyl)

But none of these popular antibiotics — or any others — can treat the flu. 

Should you take antibiotics if you have the flu?

No. Antibiotics don’t work to cure the flu. And they don’t help lessen flu symptoms in any way. 

In fact, using antibiotics when you don’t need them can cause problems. Over time, bacteria figure out how to live and multiply even with antibiotics around. This leads to antibiotic resistance. And this can make the antibiotics less effective when you need them.

Plus, like all medications, antibiotics can cause side effects. So taking them when you don’t need them puts you at risk for side effects.

Sometimes viral infections, like the flu, can lead to bacterial infections. There are times when you can develop a bacterial sinus infection, ear infection, or pneumonia because of the flu. In these cases, your provider may prescribe an antibiotic. In those cases, the antibiotic is used to treat the bacterial infection and not the flu.

How do you treat the flu?

If your flu symptoms are mild, you might not need any specific treatment at all. But when prescription treatment is needed, you’ll want an antiviral medication. 

Common antiviral medications used for the flu include:

• Oseltamivir (Tamiflu)

• Zanamivir (Relenza)

• Peramivir (Rapivab)

• Baloxavir marboxil (Xofluza)

These medications work by keeping the flu virus from infecting healthy cells. While you may still experience symptoms, taking one of these medications can make your symptoms milder and speed up your recovery time.

What to do if you think you may have the flu

The best way to protect yourself from the flu is to get a flu vaccine every year. But sometimes, your best efforts at preventing the flu don’t work. 

Here’s what to do if you develop symptoms and think you might have the flu:

• Stay away from others as much as possible.

• Consider visiting a healthcare provider for testing, especially if you’re older than 65 years old or have chronic medical conditions. 

• Take antivirals if your provider recommends them.

Here are a few other ways you can manage your flu symptoms:

• Get lots of rest. Many people who get the flu feel very tired. Get as much rest as possible to help your body recover.

• Drink lots of fluids. Keeping your body hydrated can help your immune system stay strong and fight off the flu more effectively.

• Consider taking over-the-counter (OTC) medications. If you have chronic conditions, always check with your healthcare provider before taking any.

OTC medications for flu symptom relief

Here are some OTC medications that can relieve specific symptoms:

• Fever, body aches, or a sore throat: acetaminophen (Tylenol), ibuprofen (Advil, Motrin), or naproxen (Aleve)

• Runny nose: decongestant medications, such as pseudoephedrine (Sudafed)

• Cough with mucus: guaifenesin (Mucinex)

• Dry cough: dextromethorphan (Delsym)

Can you get a flu shot when you’re taking antibiotics?

It depends. The flu shot does not interact with antibiotics. So, in theory, you can take them together. But experts recommend that you delay the flu vaccine if you have an illness with a fever. If you’re taking antibiotics for a serious infection or have a fever, wait until your symptoms are better.

Why trust our experts?

Written by:

Karla Robinson, MD

Karla Robinson, MD, is a medical editor for GoodRx. She is a licensed, board-certified family physician with almost 20 years of experience in health through varied clinical, administrative, and educational roles.

Edited by:

Sophie Vergnaud, MD

Sophie Vergnaud, MD, is the Senior Medical Director for GoodRx Health. A pulmonologist and hospitalist, she practiced and taught clinical medicine at hospitals in London for a decade before entering a career in health education and technology.

Reviewed by:

Kerry R. McGee, MD, FAAP

Kerry McGee, MD, FAAP, has over a decade of experience caring for babies, children, and teenagers as a primary care pediatrician. She has a special interest in adolescent health, particularly in adolescent mental health.

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