Azithromycin Vs. Doxycycline: Drug Comparison

Azithromycin is the active ingredient in the brand-name medication Zithromax^®. The information below is about brand name Zithromax. According to the FDA, “Generic medicines use the same active ingredients as brand-name medicines and work the same way, so they have the same risks and benefits as the brand-name medicines.”

Zithromax (azithromycin) is an antibiotic used to treat bacterial infections by inhibiting bacterial protein synthesis, preventing the growth and spread of bacteria. Its FDA-approved indications include the treatment of respiratory infections, skin infections, sexually transmitted infections, and certain ear infections. Off-label uses may include treating conditions like traveler’s diarrhea or certain tick-borne infections. Zithromax is available in tablet, liquid suspension, and intravenous forms. Common side effects include nausea, diarrhea, and abdominal pain. Caution is advised due to the risk of QT prolongation, a heart rhythm disorder, especially in patients with existing heart conditions or those taking other medications that affect heart rhythm.

Doxycycline is a broad-spectrum antibiotic used to treat a variety of bacterial infections by inhibiting protein synthesis, effectively stopping bacterial growth. Its FDA-approved indications include treatment for respiratory infections, skin infections, sexually transmitted infections, and tick-borne illnesses including Lyme disease and Rocky Mountain spotted fever. Off-label uses may include treating acne as well as certain autoimmune conditions and malaria prevention. Doxycycline is available in oral tablets, capsules, and intravenous forms. Common side effects include nausea, diarrhea, and sun sensitivity. It should not be used during pregnancy or by children under 8 due to risks of tooth discoloration and delayed bone growth.

Macrolide antibacterial

Tetracycline antibiotic

Zithromax (azithromycin) is indicated for mild to moderate infections caused by designated, susceptible bacteria:

• Sexually transmitted diseases

• Mycobacterial infections

To reduce the development of drug-resistant bacteria and maintain effectiveness of doxycycline and other antibacterial drugs, doxycycline should be used only to treat or prevent infections that are proven or strongly suspected to be caused by susceptible bacteria

• Typically taken orally once daily

• Comes in 600 mg tablets and 1,000 mg/5 mL oral suspension

• Typically taken orally once or twice daily

• Comes in 75 mg and 100 mg capsules

The most common adverse reactions are:

• Diarrhea (5%)

• Nausea (3%)

• Abdominal pain (3%)

• Vomiting

Adverse reactions have been reported in the following systems:

• Gastrointestinal

• Skin

• Renal toxicity

• Hypersensitivity

• Blood

• Other

• Patients with known hypersensitivity to azithromycin, erythromycin, any macrolide, or ketolide antibiotic

• Patients with a history of cholestatic jaundice/hepatic dysfunction associated with prior use of azithromycin

• Drug interactions: nelfinavir, warfarin

• Hypersensitivity to any of the tetracyclines

• Drug interactions: anticoagulants, penicillin, antacids, bismuth subsalicylate, barbiturates, carbamazepine, phenytoin, methoxyflurane

• Serious (including fatal) allergic and skin reactions

• Liver toxicity

• Infantile hypertrophic pyloric stenosis (IHPS)

• Prolongation of QT interval and cases of torsades de pointes have been reported

• Cardiovascular death

• Clostridioides difficile-associated diarrhea

• Zithromax may exacerbate muscle weakness in persons with myasthenia gravis

• The use of drugs of the tetracycline class, including doxycycline, during tooth development (last half of pregnancy, infancy and childhood to the age of 8 years) may cause permanent discoloration of the teeth (yellow-gray-brown)

• Clostridium difficile associated diarrhea (CDAD) has been reported with use of nearly all antibacterial agents, including doxycycline

• Intracranial hypertension (IH, pseudotumor cerebri) has been associated with the use of tetracyclines including doxycycline

• All tetracyclines form a stable calcium complex in any bone-forming tissue

• The antianabolic action of the tetracyclines may cause an increase in BUN

• Photosensitivity manifested by an exaggerated sunburn reaction has been observed in some individuals taking tetracyclines

• Pregnancy: If any tetracycline is used during pregnancy or if the patient becomes pregnant while taking these drugs, the patient should be apprised of the potential hazard to the fetus

• Breastfeeding: Because of the potential for adverse reactions in nursing infants from doxycycline, a decision should be made whether to discontinue nursing or to discontinue the drug, taking into account the importance of the drug to the mother

*This information is from the label for brand name Zithromax^®. See the Full Prescribing Information for more complete information. Azithromycin, the active ingredient in Zithromax, may also be the active ingredient in other medications, and this information may not be accurate for all medications that include the active ingredient azithromycin.

*This information is from the doxycycline label used by Alembic Pharmaceuticals Inc. See the Full Prescribing Information for more complete information. Doxycycline may also be the active ingredient in other medications, and this information may not be accurate for all medications that include the active ingredient doxycycline.