Doxycycline vs. Zithromax
See how Doxycycline and Zithromax compare on approved uses, dosing, side effects, and cost.
Key Takeaways
Doxycycline is a tetracycline antibiotic usually taken once or twice daily for a week or more, while Zithromax (azithromycin) is a macrolide often finished in a 3- to 5-day course or a single dose.
Both treat respiratory and sexually transmitted infections, but doxycycline also covers rickettsial diseases and malaria prevention, while Zithromax is approved for MAC disease prevention in HIV.
Zithromax carries a warning for cardiac QT prolongation, while doxycycline carries boxed warnings for fetal harm and tooth discoloration in young children.
Doxycycline vs. Zithromax Drug Summary
Doxycycline
Doxycycline is a tetracycline-class antibacterial used for a wide range of bacterial infections, from rickettsial diseases and chlamydia to acne and malaria prevention. It is usually taken as a capsule or tablet once or twice daily, often for a week or longer depending on the infection.
Zithromax
Zithromax (azithromycin) is a macrolide antibacterial used for respiratory, skin, and sexually transmitted infections. It is typically taken as a short course of tablets, often a 5-day taper or even a single dose, because it stays in body tissue for days.
Doxycycline vs. Zithromax Side Effects
Doxycycline
Zithromax
Doxycycline vs. Zithromax Dosage
Doxycycline
Zithromax
| STAGE | DOSE | WHEN |
| Starting dose | 200 mg total | Day 1 |
| Maximum dose | 100 mg twice daily | If needed |
| Dose changes | 6 increases | As tolerated |
| STAGE | DOSE | WHEN |
| Starting dose | 500 mg once daily | Day 1 |
| Maximum dose | 30 mg/kg single dose | If needed |
| Dose changes | 5 increases | As tolerated |
Doxycycline
| STAGE | DOSE | WHEN |
| Starting dose | 200 mg total | Day 1 |
| Maximum dose | 100 mg twice daily | If needed |
| Dose changes | 6 increases | As tolerated |
Zithromax
| STAGE | DOSE | WHEN |
| Starting dose | 500 mg once daily | Day 1 |
| Maximum dose | 30 mg/kg single dose | If needed |
| Dose changes | 5 increases | As tolerated |
Doxycycline vs. Zithromax Indications
Doxycycline
Doxycycline is FDA-approved for a broad set of infections, including rickettsial diseases like Rocky Mountain spotted fever, chlamydia, uncomplicated gonorrhea, and respiratory infections. It also has approved uses for malaria prevention, anthrax exposure, and as adjunct therapy for severe acne. Off-label, it is commonly used for Lyme disease and MRSA skin infections.
Rickettsial infections (Rocky Mountain spotted fever, typhus)
Chlamydia and uncomplicated gonorrhea
Respiratory tract infections
Malaria prevention and anthrax post-exposure prophylaxis
Off-label: Lyme disease, MRSA skin infections
Zithromax
Zithromax is FDA-approved for community-acquired pneumonia, bronchitis, sinusitis, and pharyngitis, as well as skin infections and certain sexually transmitted infections. It is also approved to prevent and treat disseminated MAC disease in people with HIV. Off-label, it is used for traveler's diarrhea and chlamydial conjunctivitis.
Community-acquired pneumonia and bronchitis
Acute sinusitis and pharyngitis/tonsillitis
Skin and skin structure infections
Chlamydia, gonorrhea urethritis/cervicitis, and chancroid
Off-label: traveler's diarrhea, chlamydial conjunctivitis
Doxycycline vs. Zithromax Pros and Cons
Doxycycline
Doxycycline covers an unusually wide range of infections, including tick-borne illness and malaria prevention, and has decades of generic pricing behind it. Because it can cause sun sensitivity and stomach upset, it typically needs to be taken with food and plenty of water, avoiding sun exposure.
Pros
Approved for a wider range of infection types, including malaria prevention
Typically $10 to $40 a month, one of the cheapest antibiotics available
Available as IV, oral capsule/tablet, and liquid suspension
Long-standing safety record with decades of clinical use
Cons
Usually requires once- or twice-daily dosing for a week or more
Can cause sun sensitivity, requiring sunscreen and reduced sun exposure
Not safe during pregnancy or for children under 8 due to tooth staining
Must be taken with enough water to avoid esophageal irritation
Zithromax
Zithromax's long tissue half-life allows short 3- to 5-day courses or even single-dose treatment for some infections, which can improve adherence. It carries a boxed-warning-level cardiac risk, so it is used cautiously in people with existing heart rhythm problems.
Pros
Often finished in 3 to 5 days, or even a single dose for some infections
Fewer pills to remember, which can improve treatment completion
No sun sensitivity restrictions like doxycycline requires
Approved for MAC disease prevention in people with HIV
Cons
Carries a warning for QT prolongation and irregular heart rhythms
Roughly $45 to $150 per course, costlier than generic doxycycline
Can cause serious, sometimes fatal liver toxicity
Not approved for rickettsial infections or malaria prevention
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