Amoxicillin vs. Zithromax
See how Amoxicillin and Zithromax compare on approved uses, dosing, side effects, and cost.
Key Takeaways
Amoxicillin is a low-cost penicillin antibiotic taken two to three times daily for 5 to 14 days, while Zithromax is a macrolide often finished in just 5 days or even a single dose.
Zithromax carries FDA warnings for QT prolongation and liver toxicity that amoxicillin's label does not include.
Amoxicillin causes rash more often, especially in people with mononucleosis, while Zithromax's most common side effect is nausea.
Amoxicillin vs. Zithromax Drug Summary
Amoxicillin
Amoxicillin is an aminopenicillin, a subtype of penicillin antibiotic, used to treat ear, sinus, throat, skin, and urinary tract infections, along with gonorrhea and H. pylori as part of combination therapy. It comes as capsules, tablets, chewable tablets, or a liquid suspension and is usually taken two to three times a day for 5 to 14 days.
Zithromax
Zithromax (azithromycin) is a macrolide antibiotic used for respiratory, skin, and certain sexually transmitted infections, as well as prevention of MAC disease in people with weakened immune systems. It comes as tablets or a liquid suspension and is often taken as a short 5-day course or a single dose, since it stays active in tissue long after the last dose.
Amoxicillin vs. Zithromax Side Effects
Amoxicillin
Zithromax
Amoxicillin vs. Zithromax Dosage
Amoxicillin
Zithromax
| STAGE | DOSE | WHEN |
| Starting dose | 1 g three times daily | At the start |
| Maximum dose | 1 g three times daily | Same as starting |
| Dose changes | None | Fixed dose |
| STAGE | DOSE | WHEN |
| Starting dose | 500 mg once daily | Day 1 |
| Maximum dose | 12 mg/kg once daily | Days 1-5 |
| Dose changes | 2 increases | As tolerated |
Amoxicillin
| STAGE | DOSE | WHEN |
| Starting dose | 1 g three times daily | At the start |
| Maximum dose | 1 g three times daily | Same as starting |
| Dose changes | None | Fixed dose |
Zithromax
| STAGE | DOSE | WHEN |
| Starting dose | 500 mg once daily | Day 1 |
| Maximum dose | 12 mg/kg once daily | Days 1-5 |
| Dose changes | 2 increases | As tolerated |
Amoxicillin vs. Zithromax Indications
Amoxicillin
Amoxicillin treats common bacterial infections of the ear, nose, throat, lungs, skin, and urinary tract, and is also used for uncomplicated gonorrhea and as part of combination therapy for H. pylori. It is not effective against viral infections and can trigger a widespread rash if given to someone with mononucleosis.
Ear, nose, and throat infections
Lower respiratory tract infections
Skin and skin structure infections
Urinary tract infections
H. pylori eradication (combination therapy)
Zithromax
Zithromax treats respiratory infections like pneumonia, bronchitis flare-ups, and sinusitis, along with skin infections and certain sexually transmitted infections such as chlamydia. It is also used to prevent and treat MAC disease in people with weakened immune systems, and is sometimes prescribed off-label for traveler's diarrhea.
Community-acquired pneumonia
Acute bacterial sinusitis
Skin and skin structure infections
Chlamydia and gonorrhea infections
MAC disease prevention and treatment
Amoxicillin vs. Zithromax Pros and Cons
Amoxicillin
Amoxicillin has been used safely for decades and remains one of the most affordable antibiotics available, with dosing forms suited to both adults and children. It does not carry the cardiac or liver warnings seen with some other antibiotic classes, but it typically requires more frequent dosing over a longer course.
Pros
Roughly $11 to $25 per month, among the cheapest antibiotics
Long track record of safety since 1974
Available in chewable tablets for children
No FDA cardiac (QT prolongation) warning
Cons
Usually dosed two to three times a day
Higher risk of rash, especially with mononucleosis
Not active against atypical bacteria like Chlamydia
Courses often run 7 to 14 days
Zithromax
Zithromax's long tissue half-life allows short courses or single-dose treatment, which can improve how reliably patients finish therapy. It covers some atypical bacteria amoxicillin does not reach, but its label carries added warnings around heart rhythm and liver safety.
Pros
Short 5-day or single-dose regimens for many infections
Covers atypical bacteria such as Chlamydia and Mycoplasma
Also approved for MAC disease prevention and treatment
Stays active in tissue for days after the last dose
Cons
Roughly $45 to $150 per course, pricier than amoxicillin
FDA warning for QT prolongation and arrhythmia risk
Risk of serious, sometimes fatal, liver toxicity
Higher rates of nausea and diarrhea in trials
Common Symptoms and Related Diseases You Can Explore
Explore a range of common symptoms the Doctronic Symptom Checker can help you understand.