Z-Pak for flu: Does azithromycin treat influenza?

In this article:

• What is a Z-Pak?
• Can a Z-Pak treat the flu?
• Why do some people feel better after a Z-Pak?
• Why might someone be prescribed azithromycin for flu symptoms?
• What treats the flu?

In this article

• What is a Z-Pak?
• Can a Z-Pak treat the flu?
• Why do some people feel better after a Z-Pak?
• Why might someone be prescribed azithromycin for flu symptoms?
• What treats the flu?

Azithromycin is a commonly prescribed antibiotic used for various infections, including some sexually transmitted diseases (STDs) and bacterial pneumonia. Because it’s a popular prescription for infections, many people may request azithromycin or a Z-Pak when they come down with severe cold or flu-like symptoms. However, antibiotics aren’t always the solution for infections and can cause avoidable side effects, contribute to antibiotic resistance, and delay the right treatment if used when not needed. In this article, learn about azithromycin and Z-Paks, why they don’t work against influenza, and when they might still be used during flu season.

What is a Z-Pak?

A Z-Pak or Z-Pack is the shortened name for a brand-name course of azithromycin called Zithromax Z-Pak. Zithromax (azithromycin) is a macrolide antibiotic similar to clarithromycin and erythromycin. These types of antibiotics work by blocking protein synthesis, which stops bacteria from replicating. 

Z-Paks are usually effective for infections such as:

• Pneumonia caused by bacteria Streptococcus pneumoniae, Haemophilus influenzae, or Moraxella catarrhalis caught outside of a hospital setting 
• Ear infections
• Strep throat infections caused by Streptococcus pyogenes
• Skin infections caused by Streptococcus pyogenes, Streptococcus agalactiae, or Staphylococcus aureus
• Sexually transmitted infections such as chlamydia, gonorrhea, and infections caused by Haemophilus ducreyi and Mycoplasma genitalium

Z-Paks aren’t approved by the Food and Drug Administration (FDA) to treat the flu, which is caused by the influenza virus. 

Can a Z-Pak treat the flu?

No, a Z-Pak doesn’t effectively treat the flu because influenza is caused by a virus, and antibiotics like azithromycin only work against bacterial infections. 

“Antibiotics only work on bacteria, yet patients often think that any infection that presents with a cough, fever, or malaise requires it,” explains Kiara DeWitt, RN, certified neurology nurse at Cook Children’s Medical Center and Head of Clinical Operations at Medical Director Co. 

Taking an antibiotic when it’s not needed won’t help you recover faster, and you may run the risk of getting side effects. “Patients must understand that antibiotics work on bacteria, not viruses, so an antibiotic will not be able to kill a flu, cold, or COVID-19 virus,” says Edmond Hakimi, DO, physician and Medical Director at Wellbridge in Long Island, New York. 

“Also, misusing antibiotics can create bacteria that become resistant to antibiotics, meaning that the antibiotics will no longer kill that certain bacteria, and this is a serious concern for public health,” Dr. Hakimi adds. Healthcare providers are especially careful about not prescribing Z-Paks for infections likely to be viral (not bacterial) because unnecessary antibiotic use contributes to antibiotic resistance, leading to the emergence of bacterial strains that are harder to treat. 

Why do some people feel better after a Z-Pak?

It’s common to hear people say that a Z-Pak helped with their flu, but the explanation is more complicated than the antibiotic curing the viral infection. In laboratory and animal studies, azithromycin has shown some antiviral and anti-inflammatory activity, but these effects have not been observed in human studies with the influenza virus.

Several factors may explain why someone with the flu feels better after starting a Z-Pak. First, many viral infections naturally improve within a few days as the immune system can take time to clear the infection. Some people may also have had a secondary bacterial infection (one that occurs after a viral infection) that responds to azithromycin treatment. Azithromycin can also make certain symptoms feel less intense since it reduces inflammation, even if it isn’t treating the flu itself. Although people may have felt better after a Z-Pak, the current evidence doesn’t support using it to treat the flu. 

“While the patient may feel better temporarily due to the drug’s anti-inflammatory component, the viral load itself would remain untouched. Additionally, it breeds antibiotic resistance, so the next time the patient does have a bona fide bacterial infection, treatment may not work as well,” DeWitt says. 

Why might someone be prescribed azithromycin for flu symptoms?

Although azithromycin doesn’t treat the flu itself, a healthcare professional may prescribe it if they suspect a bacterial infection is developing alongside a viral illness. A prescriber might recommend antibiotics if they see an ambiguous mix of symptoms of viral and bacterial infection, such as prolonged fever lasting more than four days, or the presence of a productive cough with purulent (discolored) sputum, DeWitt says. 

Bacterial infections that can occur during or after an influenza infection include:

• Bacterial pneumonia
• Bacterial sinus infection
• Ear infections
• Strep throat
• Bacterial bronchitis

Clinicians also become more cautious when flu symptoms initially improve and then suddenly worsen, a common sign of a secondary bacterial infection. Other red flags include a persistent or returning fever, chest pain, trouble breathing, a severe sore throat, or symptoms that last longer than seven to 10 days. Seek medical attention if you notice these symptoms of worsening infection. 

Though yellow or green mucus is a common sign of a bacterial infection, it’s not enough to prove that it’s a bacterial infection. Bacterial and viral illnesses are only some of the reasons for discolored mucus. To make an accurate diagnosis, healthcare professionals may perform a physical exam, review your clinical history, or do tests such as a nose or throat swab. “Influenza can be identified through a rapid antigen test or PCR test (viral RNA identification) within 15 minutes to a few hours,” explains DeWitt. “Bacterial infection either requires culture confirmation or a minimum laboratory marker to support the presence of bacteria, such as an elevated white blood cell count or C-reactive protein greater than 10 mg/L to justify the prescription of an antibiotic,” she says.

Azithromycin is prescribed only when there’s a strong suspicion of a bacterial infection, and it’s not been shown to shorten the duration or reduce the severity of influenza in human clinical trials.

What treats the flu?

Most flu infections improve without treatment after several days, but supportive care and early treatment with an antiviral medication can make a difference in feeling comfortable. While a Z-Pak likely won’t help, there are several evidence-backed options that can.

Lifestyle and home care

There are some natural lifestyle treatments you can do at home to support your recovery. For example:

• Rest can help the immune system fight the virus effectively.
• Drinking lots of fluids helps prevent dehydration from fever/sweating, vomiting, or diarrhea.
• Humidifiers, warm showers, and saline nasal sprays can help with congestion and throat discomfort.

“Viral infections, such as influenza, are self-limiting and resolve by virtue of the immune system clearing the virus in seven to 10 days if given proper rest and hydration,” DeWitt says.

Over-the-counter (OTC) relief

OTC medications can help reduce fever, body aches, and congestion that can come with the flu. Common OTC remedies include:

• Acetaminophen
• Non-steroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen or naproxen
• Decongestants such as Sudafed (pseudoephedrine) and Afrin (oxymetazoline)
• Cough suppressants such as Delsym or Robitussin DM

Because cold and flu products often contain a combination of drugs, it’s best to discuss treatments with your healthcare provider to tailor them to your symptoms. Follow dosing instructions closely.

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Prescription antivirals

Antiviral medications are the only treatments that act directly against the influenza virus. “If the flu is caught early, antiviral medications such as Tamiflu, rest, hydration, and symptom management can fight off the virus,” Dr. Hakimi says. Examples of antivirals include:

• Tamiflu (oseltamivir)
• Relenza (zanamivir)
• Rapivab (peramivir)
• Xofluza (baloxavir marboxil)

These medications can shorten the flu and reduce complications, especially for people at higher risk, like older adults with weakened immune systems. These medications work best when taken within 48 hours of flu symptom onset, so getting seen by a healthcare provider early on is key. 

Prevention

The most effective way to avoid the flu is through preventive measures. A flu shot can help reduce the risk of infection and lower the severity of symptoms if you do get sick. Practice hand hygiene (handwashing and sanitizing), avoid close contact with sick people, and stay home if you are sick to prevent spreading illnesses like the flu. 

Whether you have a viral or bacterial infection, SingleCare can help you save on antibiotics like a Z-Pak and flu medications. SingleCare is free to sign up for and use, and can even help you save on over-the-counter products like saline nasal spray with a prescription from your healthcare provider. You can save up to 80% on medications with a SingleCare coupon and a valid prescription, and coupons can be used at many major retail pharmacies. 

Bottom line: Z-paks do not treat the flu

Antibiotics like Z-Paks do not treat the influenza virus. Though it can be useful in subsequent bacterial infections, there’s no strong evidence that azithromycin can be helpful in humans with the flu. There are other ways to treat the flu effectively. 

In any case, talk to your healthcare provider as soon as you have symptoms of an infection. They can clinically evaluate your symptoms and test for the flu with a rapid in-office test. They can recommend the safest and most effective treatment plan based on your symptoms, test results, and health history. “Medicine is most effective when decisions are based on data, not ritual. In the long run, every time a clinician avoids the unnecessary prescription of antibiotics, the efficacy of those same antibiotics is prolonged for patients of the future,” DeWitt says.