Amoxicillin vs. Doxycycline

See how Amoxicillin and Doxycycline compare on approved uses, dosing, side effects, and cost.

Key Takeaways

  • Amoxicillin and doxycycline are both effective oral antibiotics, but they come from different drug classes and target different bacteria.

  • Amoxicillin is generally safe in pregnancy and young children, while doxycycline is avoided in both due to fetal and tooth-development risks.

  • Doxycycline covers a broader range of infections, including tick-borne diseases and STIs, while amoxicillin is a first-line choice for common ear, sinus, and urinary infections.

Amoxicillin vs. Doxycycline Drug Summary

Amoxicillin

Amoxicillin is an aminopenicillin antibiotic used to treat common bacterial infections of the ear, sinus, throat, lungs, skin, and urinary tract. It is taken by mouth as a capsule, tablet, chewable, or liquid, usually two to three times a day, and has been used safely since 1974.

Doxycycline

Doxycycline is a tetracycline-class antibiotic used for infections ranging from respiratory illness and chlamydia to tick-borne diseases like Rocky Mountain spotted fever. It is taken by mouth as a capsule, tablet, or liquid, typically once or twice daily, and has been available since 1967.

Amoxicillin vs. Doxycycline Side Effects

Amoxicillin

Most common
Vomiting (greater than 1%)
Nausea (greater than 1%)
Rash (greater than 1%)
Diarrhea (greater than 1%)

Doxycycline

Most common
Vomiting (common)
Nausea (common)
Rash (common)
Diarrhea (common)

Amoxicillin vs. Doxycycline Dosage

Amoxicillin

Dosage
Dosage Table
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

Doxycycline

Dosage
Dosage Table
STAGE DOSE WHEN
Starting dose 200 mg total, split doses Day 1
Maximum dose 100 mg twice daily If needed
Dose changes 5 increases As tolerated

Amoxicillin vs. Doxycycline Indications

Amoxicillin

Amoxicillin is FDA-approved for common bacterial infections of the ear, nose, throat, lungs, skin, and urinary tract, as well as gonorrhea and, in combination regimens, H. pylori. It does not work against viral infections and can trigger a distinctive rash in people with mononucleosis.

  • Ear, nose, and throat infections

  • Lower respiratory tract infections

  • Skin and skin structure infections

  • Urinary tract infections

  • H. pylori eradication (combination therapy)

Doxycycline

Doxycycline covers a broader range of infections, including tick-borne rickettsial diseases, chlamydia, and inhalational anthrax exposure, plus off-label uses like Lyme disease and acne. It is not approved for children under 8 for routine infections or for use during pregnancy, due to risks to developing teeth and the fetus.

  • Rocky Mountain spotted fever and rickettsial infections

  • Chlamydia and uncomplicated gonorrhea

  • Anthrax post-exposure prophylaxis

  • Malaria prophylaxis

  • Lyme disease treatment (off-label)

Amoxicillin vs. Doxycycline Pros and Cons

Amoxicillin

Amoxicillin has a long safety record and a straightforward dosing schedule, making it a common first choice for everyday bacterial infections. It is generally well tolerated but carries a real risk of allergic reaction in people with penicillin sensitivity.

Pros

  • Considered safe during pregnancy

  • Approved for children of all ages, including infants

  • Fewer restrictions on sun exposure or food timing

  • Well-established safety profile after decades of use

Cons

  • Not effective against tick-borne or rickettsial infections

  • Higher risk of allergic and anaphylactic reactions

  • Narrower spectrum, misses many atypical bacteria

  • Can cause a significant rash in patients with mono

Doxycycline

Doxycycline covers a broader range of bacteria, including atypical and tick-borne organisms, and is also used for acne and certain STIs beyond amoxicillin's reach. Its tradeoffs include sun sensitivity and restrictions in young children and pregnancy.

Pros

  • Broader spectrum, covers atypical and tick-borne bacteria

  • Also used for acne, rosacea, and STI treatment

  • Simple once- or twice-daily dosing for most infections

  • Effective for malaria and anthrax prophylaxis

Cons

  • Not recommended in pregnancy due to fetal risk

  • Can cause permanent tooth discoloration in young children

  • Requires sun protection due to photosensitivity risk

  • Must be taken with plenty of water to avoid esophageal irritation

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