Azithromycin vs. Amoxicillin: What's the Difference? (2024)

Azithromycin and amoxicillin are commonly prescribed antibiotics used to treat various bacterial infections, such as pneumonia, bronchitis, or urinary tract infections (UTIs).

While azithromycin and amoxicillin are antibiotics, they are classified as different types of antibiotics, macrolide antibiotics vs. penicillin-like antibiotics, respectively.

Furthermore, they differ in the infections they treat, side effects, and drug interactions.

Continue reading to learn more about azithromycin vs. amoxicillin.

Understanding Antibiotics

Antibiotics are prescription medications used to treat bacterial infections (infections caused by bacteria). They work by killing or stopping bacteria from growing inside the body.

Further examples of bacterial infections include strep throat and ear infections. Antibiotics do not treat viral infections such as the common cold, the flu, or COVID-19.

What Is Azithromycin?

Azithromycin is classified as a macrolide antibiotic that prevents bacterial infections from spreading inside the body.

Azithromycin is commonly known by its brand name, the orally administered Zithromax, also known as the Zithromax Z-Pak.

FDA-Approved Uses

Azithromycin is approved by the Food and Drug Administration (FDA) to treat certain bacterial infections, including:

• Bronchitis
• Pneumonia
• Certain sexually transmitted infections (STIs)
• Certain infections involving the lungs, ears, throat, sinuses, skin, and reproductive organs

It can also be used to treat or prevent a type of lung infection associated with human immunodeficiency virus (HIV) called Mycobacterium aviumcomplex (MAC) infection.

Off-Label Uses

Off-label prescribing is when a medication is used in a way or for a purpose for which it was not originally FDA-approved.

Sometimes, healthcare providers may prescribe azithromycin off-label for infants that are younger than indicated (approved by the FDA).

Healthcare providers may prescribe higher doses of azithromycin than FDA-approved. In both cases, these would be examples of off-label uses.

Other examples of off-label azithromycin use include but are not limited to:

• Treatment of trachoma (a bacterial eye infection)
• Maintenance treatment in people who frequently have worsening of chronic obstructive pulmonary disease (COPD), which includes lung diseases such as emphysema and chronic bronchitis that make breathing difficult

Forms of Administration

Azithromycin is available in various dosage forms, including:

• Oral tablets
• Oral suspension (liquid)
• Single-dose suspension
• Injection
• Eye drops (under the brand name Azasite)

What Is Amoxicillin?

Amoxicillin is classified as a penicillin-like antibiotic that works by stopping bacteria from growing.

Amoxicillin is known in its brand-name product form, Amoxil, although most forms are only available as generic products (no brand-name affiliation).

FDA-Approved Uses

The FDA has approved amoxicillin to treat certain bacterial infections, including:

• Pneumonia
  
• Bronchitis
• Infections of the ears, nose, throat, urinary tract, and skin

Amoxicillin is also prescribed along with other medications to treat Helicobacter pylori (H. pylori), a bacteria that causes ulcers (sores on the lining of the esophagus, stomach, or small intestine).

Off-Label Uses

Some examples of off-label amoxicillin prescribing include but are not limited to:

• Treat actinomycosis (a long-term bacterial infection commonly involving the face and neck)
• Treat bacterial bone and joint infections.

Forms of Administration

Amoxicillin is available in various dosage forms, including:

• Oral tablets
• Oral chewable tablets
• Oral capsules
• Oral suspension (liquid)

Amoxicillin in Other Products

While this article focuses on single-ingredient amoxicillin, amoxicillin is also an ingredient in other medications, such as:

• Augmentin (amoxicillin and clavulanic acid): The clavulanic acid is added to prevent bacteria from destroying amoxicillin.
• Talicia (amoxicillin, omeprazole, and rifabutin): This fixed-dose combination medicine treats H. pylori infection.
  

Dosing Guidelines

General dosing guidelines for each medication follow.

Azithromycin

Azithromycin can be taken with or without food.

This drug can be given to adults and children, with dosing in children based on the infection type and the child's weight.

Always use a medicinal measuring device when measuring the liquid medication.

For adults, the dose depends on the type of infection:

• A standard dosage for many infections is the Z-Pak: 500 milligrams (mg) by mouth on the first usage dose, from there, 250 mg once daily on days two through five.
• For sinus infections or certain other types, a typical dose is 500 mg orally daily for three days.
• For chancroid (a highly contagious sexually transmitted infection that causes genital ulcers) or nongonococcal (not caused by gonorrhea bacteria) urethritis (inflammation of the tube that carries urine from the bladder to outside the body) and cervicitis (inflammation of the cervix, the canal connecting the uterus and vagin*) healthcare providers prescribe a single 1,000 mg (1 gram) dose.
• For gonococcal (caused by gonorrhea bacteria) urethritis and cervicitis, healthcare providers prescribe a 2,000 mg dosage.
  

Amoxicillin

Amoxicillin can be taken with or without food.

This drug can be given to adults and children. Dosing in children depends on infection type and the child's weight.

Always use a medicinal measuring device, such as a medicine spoon or cup, when measuring the liquid suspension form of administration.

For adults, the dose depends on the type of infection, as follows:

• For mild to moderate ear, nose, throat, skin, or genitourinary tract infections (diseases of the genital and urinary organs), typical doses are 500 mg by mouth every 12 hours or 250 mg by mouth every eight hours.
• For severe ear, nose, throat, skin, or genitourinary tract infections, typical doses are 875 mg by mouth every 12 hours or 500 mg by mouth every eight hours.
• For severe lower respiratory tract infections (such as pneumonia or bronchitis), typical doses are 875 mg by mouth every 12 hours or 500 mg by mouth every eight hours.

Your healthcare provider will determine the length of treatment by the type and severity of infection.

The length of treatment is usually anywhere from five to 14 days but could be longer in some cases.

Why Do I Need to Finish My Antibiotics?

When taking an antibiotic, it is crucial to finish the entire course of the prescription, even if you start to feel better after a few days.

Take your antibiotic as prescribed, and do not skip doses.

Finishing your antibiotic helps ensure the infection is completely cleared and helps prevent antibiotic resistance.

This occurs when antibiotics are no longer effective against the bacteria they were created to kill.

Which Is More Effective?

Studies have found azithromycin and amoxicillin to be similarly effective and well-tolerated.

One review of many studies found that of the two, azithromycin may be safer and better tolerated in children with ear infections.

However, because both drugs are considered safe and effective, and because there are many factors to consider when selecting the most appropriate antibiotic, your healthcare provider will decide which antibiotic is best for your bacterial infection.

Side Effects and Safety

Although side effects vary slightly, there are a few potentially severe side effects to note that can apply to either antibiotic, including:

• If you experience symptoms of an allergic reaction after using azithromycin or amoxicillin, such as urticaria (hives), difficulty breathing, swallowing, or swelling of the face, lips, tongue, or throat, seek emergency medical help.
• If you have symptoms of a skin reaction, such as fever, burning eyes, skin pain, rash, or blistering or peeling skin, seek emergency medical help immediately.
• In some cases, antibiotic-associated diarrhea may occur, ranging from mild to life-threatening. This can even occur up to several months after finishing the antibiotic. Symptoms can include watery or bloody diarrhea and may be accompanied by fever and stomach pain. If this occurs, notify your healthcare provider immediately.

Contact your healthcare provider immediately if you or a loved one experiences severe side effects.

Call 911 if your symptoms feel life-threatening or if you think you or a loved one are experiencing a medical emergency.

The section below will outline the common and severe side effects that azithromycin or amoxicillin may cause.

Azithromycin

Common side effects of azithromycin may include:

• Nausea
• Vomiting
• Diarrhea
• Headache

Severe side effects of azithromycin may include:

• Symptoms of jaundice, such as yellowing of the skin or whites of the eyes
• Upper stomach pain
• Flu-like symptoms
• Muscle weakness
  
• Lethargy
• Unusual bleeding or bruising
• Appetite loss
• Pink and swollen eyes
• Infants less than 6 weeks old: vomiting or irritability while feeding

Amoxicillin

Common side effects of amoxicillin may include:

• Nausea
• Vomiting
• Diarrhea
• Altered taste
• Headache

Severe side effects of amoxicillin may include:

• Rash
• Skin blisters or peeling
• Itching
• Hives
• Wheezing
  

Potential for Interaction

Before taking an antibiotic, ensure your healthcare provider knows if you are allergic to any medications.

Also, make sure your provider knows about all the medications you take, including:

• Prescription medications
• Over-the-counter (OTC) medicines
• Vitamins
• Supplements
  

Azithromycin-Specific Interactions

Examples of medications that may interact with azithromycin include:

• Blood-thinning medications, such as Jantoven (warfarin)
• Anti-inflammatory medications used for gout, such as Mitigare (colchicine)
• Immunosuppressive drugs used to treat organ rejection post-transplant, such as Sandimmune (cyclosporine)
• Drugs used for the treatment of heart failure (HF), such as Lanoxin (digoxin)
• Drugs used to treat and prevent seizures, such as Dilantin (phenytoin)
• Drugs used to treat heart rhythm problems, such as Cordarone (amiodarone)
• Drugs used for the treatment of multiple sclerosis (MS), such as generic quinidine
• Drugs used to treat human immunodeficiency virus (HIV), such as Viracept (nelfinavir)
• Antacids that contain aluminum or magnesium hydroxide, such as Tums (if taking with azithromycin, doses of each should be spaced at least two hours apart, but consult with your prescribing provider or pharmacist on proper scheduling)

Amoxicillin-Specific Interactions

Examples of medications that may interact with amoxicillin include:

• Other anti-inflammatory medications, such as Probalan (probenecid) or Aloprim (allopurinol)
• Jantoven (warfarin)

Summary

Azithromycin and amoxicillin are two orally administered FDA-approved prescription antibiotics used to treat various infections caused by bacteria.

While generally viewed as similarly safe and effective by experts, they carry notable differences that consumers should be aware of.

Azithromycin and amoxicillin are different types of antibiotics, macrolide antibiotics vs. penicillin-like antibiotics, respectively.

They differ in the infections they treat, side effects, and drug interactions.

Consult your healthcare provider for more information about each medication and medical advice about the appropriate prescription.