Amoxicillin (Moxatag) vs. Azithromycin (Zithromax)

• Amoxicillin and azithromycin are antibiotics used to treat bacterial infections of the middle ear, tonsils, throat, larynx (laryngitis), bronchi (bronchitis), lungs (pneumonia), urinary tract, skin, and some sexually transmitted diseases.
• Amoxicillin and azithromycin are different types of antibiotics. Amoxicillin is a penicillin-type antibiotic and azithromycin is a macrolide antibiotic.
• Brand names of amoxicillin include Moxatag and Amoxil.
• Brand names of azithromycin include Zithromax, Zithromax Tri-Pak, Zithromax Z-Pak, and Zmax.
• Side effects of amoxicillin and azithromycin that are similar include diarrhea, abdominal pain, nausea, vomiting, heartburn/indigestion, and rash.
• Side effects of amoxicillin that are different from azithromycin include dizziness, sleep problems (insomnia), itching, confusion, easy bruising, bleeding, and allergic reactions.
• Side effects of azithromycin that are different from amoxicillin include nervousness, vaginitis, tongue discoloration, and ringing in the ears.

Amoxicillin is a penicillin-type antibiotic, in the same class as ampicillin (Unasyn), piperacillin (Pipracil), and ticarcillin (Ticar). Penicillin-type antibiotics do not directly kill bacteria, but they stop bacteria from multiplying by preventing them from forming the walls that surround them. Bacterial walls protect bacteria from their environment and keep the contents of the bacterial cell together. Bacteria are unable to survive without a cell wall. Amoxicillin is effective against several different bacteria such as H. influenzae, N. gonorrhoea, E. coli, Streptococci, Pneumococci, and some strains of Staphylococci. Amoxicillin is used to treat bacterial infections of the middle ear, throat, tonsils, larynx (laryngitis), lungs (pneumonia), bronchi (bronchitis), urinary tract, and skin. It also is used to treat gonorrhea.

Azithromycin is a macrolide antibiotic chemically related to erythromycin and clarithromycin (Biaxin) used to treat otitis media (infection of the middle ear), tonsillitis, laryngitis, bronchitis, pneumonia, sinusitis, uncomplicated skin and skin structure infections, Mycobacterium avium complex, acute bacterial flare ups of chronic obstructive pulmonary disease (COPD), acute pelvic inflammatory disease, and several sexually transmitted infectious diseases (STDs) such as nongonococcal urethritis and cervicitis. It is effective against a wide variety of bacteria such as Hemophilus influenzae, Streptococcus pneumoniae, Mycoplasma pneumoniae, Staphylococcus aureus, mycobacterium avium, and many others.

Amoxicillin

Side effects due to amoxicillin include

• diarrhea,
• dizziness,
• heartburn,
• insomnia,
• nausea,
• itching,
• vomiting,
• confusion,
• abdominal pain,
• easy bruising,
• bleeding,
• rash, and
• allergic reactions.

People who are allergic to the cephalosporin class of antibiotics, which are related to the penicillins, for example, cefaclor (Ceclor), cephalexin (Keflex), and cefprozil (Cefzil), may or may not be allergic to penicillins.

Serious but rare reactions include:

• seizures,
• severe allergic reactions (anaphylaxis), and
• low platelet (thrombocytopenia) or red blood cell count.

Amoxicillin can alter the normal bacteria in the colon and encourage overgrowth of some bacteria such as Clostridium difficile which causes inflammation of the colon (pseudomembranous colitis). Patients who develop signs of pseudomembranous colitis after starting amoxicillin (diarrhea, fever, abdominal pain, and possibly shock) should contact their physician immediately.

Azithromycin

The most common side effects of azithromycin are:

• Diarrhea or loose stools
• Nausea
• Abdominal pain
• Vomiting

Other possible side effects of azithromycin include:

• Rash
• Nervousness
• Vaginitis
• Tongue discoloration
• Ringing in the ears
• Indigestion

Possible serious side effects of azithromycin include:

• Angioedema
• Abnormal liver tests
• Cholestatic jaundice
• Steven-Johnson Syndrome
• Serious allergic reactions
• Abnormal heart beats

Antibiotics can alter the normal bacteria in the colon and encourage overgrowth of some bacteria such as Clostridium difficile, which causes inflammation of the colon (pseudomembranous colitis). Patients who develop signs of pseudomembranous colitis after starting azithromycin (diarrhea, fever, abdominal pain, and possibly shock) should contact their physician immediately.

Amoxicillin

• For most infections in adults the dose of amoxicillin is 250 mg every 8 hours, 500 mg every 8 hours, 500 mg every 12 hours or 875 mg every 12 hours, depending on the type and severity of infection.
• For the treatment of adults with gonorrhea, the dose is 3 g given as one dose.
• For most infections, children older than 3 months but less than 40 kg are treated with 25 or 45 mg/kg/day in divided doses every 12 hours or 20 or 40 mg/kg/day with one-third of the daily dose given every 8 hours depending on the type and severity of the infection.
• Amoxicillin can be taken with or without food.

Azithromycin

• Azithromycin (except Zmax) can be taken with or without food, but food reduces stomach upset.
• Zmax should be taken on an empty stomach 1 hour before or 2 hours after a meal since food reduces its absorption.
• The adult azithromycin dose is 500-2000 mg in multiple or single doses.
• For most infections, azithromycin is taken once daily for a relatively short course of treatment (usually five days).
• The first dose is often a "double dose," twice as much as the remainder of the doses given.
• For acute bacterial sinusitis, azithromycin way be taken once daily for three days.
• Zmax usually is given as a single 2 gm dose.

Amoxicillin

Amoxicillin is rarely associated with important drug interactions.

Azithromycin

Azithromycin (except Zmax) should not be taken at the same time as aluminum- or magnesium-based antacids, such as Mylanta or Maalox, because antacids will bind the azithromycin and prevent it from being absorbed from the intestine.

Amoxicillin

• Penicillins are generally considered safe for use by pregnant women who are not allergic to penicillin.
• Small amounts of amoxicillin may be excreted in breast milk and may cause diarrhea or allergic responses in nursing infants. Amoxicillin is generally considered safe to use while breastfeeding. Amoxicillin is used to treat infections in the newborn.

Azithromycin

• There are no adequate studies of azithromycin in pregnant women. Azithromycin should only be used during pregnancy if it is clearly necessary.
• It is not known if azithromycin is secreted in breast milk.