Zithromax Side Effects

The Food and Drug Administration has received 15,312 reports of adverse events associated with Zithromax, according to the most recent FDA data from March 2024.
The FDA Adverse Event Reporting System shows 12,161 — or roughly 80% — of the reports involved serious adverse events, including 659 deaths.

Disclaimer: Because of potential under-reporting as well as limitations caused by potential inaccurate, incomplete, unverified and/or untimely information FAERS data alone cannot represent all safety information on Zithromax. Consult a health care professional before stopping or changing medication.

Drug hypersensitivity is the most commonly reported adverse reaction to Zithromax, followed by drug ineffectiveness, diarrhea, nausea and vomiting.

The top three most commonly reported adverse reactions to Zithromax comprise just over 25% of all adverse side effects reported to the FDA.

Common side effects of Zithromax include gastrointestinal issues, nervous system symptoms and cardiovascular symptoms, according to the drug’s prescribing information updated in April 2024. Most common side effects are mild, but patients should contact their provider if they experience any adverse reactions.

The types of adverse reactions seen in clinical trials were similar in pediatric and adult patients. Diarrhea, abdominal pain, vomiting, nausea, and rash were reported the most.

Adverse reactions that occurred with a frequency of 1% or less in children included respiratory, skin, blood and nervous system symptoms. Symptoms such as cough, eczema and nasal congestion are generally mild. However, anemia and low white blood cell counts could cause lasting damage. Nervous system symptoms, including agitation and insomnia, can disrupt a child’s normal behavior.

Serious side effects of Zithromax include negative impacts on the heart and liver and severe allergic reactions that can be lethal, according to highlights of the April 2024 prescribing information. In rare cases, intravenous administration has been linked to a severe drop in blood pressure known as sudden hypotension.

Zithromax and Hypersensitivity

Patients on azithromycin, the active ingredient in Zithromax, have experienced serious allergic reactions, including swelling and anaphylaxis. Reported skin reactions include pustules, Stevens-Johnson syndrome and toxic epidermal necrolysis.

“The exact mechanisms causing severe allergic reactions to Zithromax are not fully understood,” Dr. Ramit Singh Sambyal told Drugwatch. “It’s likely a complex interplay between the immune system and the drug’s structure.”

Sambyal, who is a general physician, said doctors need to review a thorough medical history of patients’ allergies when prescribing Zithromax.

There are also reports of fatalities and drug reactions with systemic symptoms such as eosinophilia. Those with eosinophilia have a high count of eosinophils, which are a type of white blood cell. This may indicate a heightened immune response after experiencing an allergic reaction to Zithromax.

Despite an initially successful treatment of allergy symptoms, some patients had a resurgence of hypersensitivity symptoms even after they discontinued Zithromax. These patients required prolonged periods of observation and treatment. Doctors don’t yet know the relationship between these episodes, how long azithromycin stays in the body and the duration of allergen exposure.

Zithromax and Hepatotoxicity

Zithromax use can negatively impact the liver, sometimes fatally. Most people recover from Zithromax-related hepatotoxicity (toxic liver damage) within four to eight weeks. Side effects like jaundice and liver issues, however, can last six months or longer. Severe cases of liver failure can lead to an emergency liver transplant or death.

“For patients with pre-existing liver disease, monitoring is crucial,” Sambyal said. “Best practices include baseline liver function tests and potentially repeating them mid-treatment, especially for prolonged courses.”

Cholestatic hepatitis, an inflammation of the liver, can be typical within one to three weeks of starting the medication. However, the condition is usually temporary and benign.

QT Prolongation

Long QT syndrome, a type of conduction disorder that causes problems with the electrical system that controls your heart, has been seen with the class of drugs that includes azithromycin. Zithromax, along with similar medications, can increase the risk of developing other conduction disorders, including cardiac arrhythmia and torsades de pointes, a type of abnormal heartbeat.

Palpitations, chest discomfort, dizziness, feeling faint or an irregular heartbeat could be symptoms of QT prolongation. The risk of experiencing this side effect is higher in older people, individuals with a familial history of prolonged QT or low blood potassium and those who take certain medications to control heart rhythm.

Cardiovascular Death

A 2020 study reported in Jama Networkk found that azithromycin is related to increased cardiovascular death and all-cause mortality, compared to patients taking a different antibiotic, amoxicillin. Researchers noted that the potential risk was greater during the first five days of azithromycin.

According to the drug’s prescribing information, doctors should, “consider balancing this potential risk with treatment benefits when prescribing Zithromax.”

Clostridioides Difficile-Associated Diarrhea (CDAD)

Reports of Clostridioides difficile-associated diarrhea occur with the use of nearly all antibiotics, including Zithromax. The symptoms can range from mild diarrhea to fatal bowel inflammation. Because treatment with antibiotics alters the microbiome of the colon, antibiotic use may lead to an overgrowth of C. difficile.

C. difficile is an antibiotic-resistant bacteria. Quick treatment is crucial to managing infection. Symptoms typically appear between five and 10 days after you begin the medication, but sometimes it can take up to two months. Age, underlying disease and prolonged hospital stays increase the risk of CDAD.

Exacerbation of Myasthenia Gravis

Several medications can aggravate myasthenia gravis, but Zithromax is the most common to do so, according to a 2021 article published in the Journal of Clinical Medicine.
MG is an autoimmune condition that leads to weak muscles. Symptoms of MG include breathing and swallowing difficulties, double or blurred vision, drooping eyelids and weakness in the arms and legs.

If you experience any serious side effects, you should consult your doctor. Additionally, you may consider reporting any side effects you experience to the FDA’s MedWatch Adverse Event Reporting program.

The FDA has released a few warnings about Zithromax, primarily related to long-term use.

In March 2013, the FDA announced the azithromycin drug labels had been updated with stronger warnings related to the risk of QT interval prolongation and torsades de pointes, a specific, rare heart rhythm abnormality.

In an August 2018 safety announcement, the FDA warned about an increased risk of cancer relapse with long-term use of Zithromax after donor stem cell transplant.

Patients should always check for label warnings and ask a medical provider or pharmacist how to take antibiotics safely.

If you are already at risk for one or both of these conditions, discuss the risks and benefits of taking Zithromax with your health care provider before taking it.

Lifestyle changes, especially ones that focus on digestive health, can help minimize or eliminate many antibiotic side effects. Stay hydrated by drinking plenty of water to reduce headaches and abstain from consuming alcohol to reduce chances of dehydration.

While Zithromax can hinder appetite, it’s important to eat a well-rounded and nutritious diet to stave off nausea. You can combat the appetite-suppressant effects of Zithromax by eating smaller meals more frequently.

Antibiotics can potentially cause diarrhea or ultra-soft stools because the medications alter the body’s microbiome. Taking a probiotic can reintroduce good bacteria into your system.

There are several Zithromax antibiotic alternatives. The major differences lie in the drug class they belong to.

Penicillin and cephalosporin both kill bacteria by preventing their cell walls from forming. Fluoroquinolone, on the other hand, kills bacteria by preventing it from creating DNA.

Tetracycline and macrolides, the class of antibiotics that Zithromax belongs to, prevent bacteria from multiplying by inhibiting their protein productions. Tetracycline and macrolides usually take longer to take effect compared to penicillin.

Because antibiotics treat a wide range of infections, the right alternative depends on the patient’s condition and needs.

Zithromax side effects are often serious. Closely monitor any adverse reactions and contact your provider if they worsen or do not go away after several days.

Editor Lindsay Donaldson contributed to this article.