Choose amoxicillin for uncomplicated bacterial infections like strep throat or ear infections. Select doxycycline for more complex infections, including those caused by atypical bacteria like Chlamydia or Mycoplasma, as well as some tick-borne illnesses like Lyme disease.
Antibiotic Class and Mechanism
Amoxicillin is a penicillin-derivative, inhibiting bacterial cell wall synthesis. Doxycycline belongs to the tetracycline family, preventing bacterial protein synthesis. This difference influences their effectiveness against various bacterial species.
Spectrum of Activity
- Amoxicillin: Effective against Gram-positive bacteria (like Streptococcus and Staphylococcus) and some Gram-negative bacteria (like Haemophilus influenzae). Doxycycline: Broader spectrum, effective against both Gram-positive and Gram-negative bacteria, as well as atypical bacteria and some parasites.
Dosage and Administration
Dosage depends on the infection’s severity, patient’s age, and weight. Always follow your doctor’s prescription. Amoxicillin is usually taken orally, while doxycycline can be administered orally or intravenously, depending on the situation. Doxycycline absorption can be affected by dairy products and antacids. Take it on an empty stomach with water.
Side Effects
- Amoxicillin: Common side effects include diarrhea, nausea, vomiting, and allergic reactions (rash, itching, swelling). Serious, albeit rare, side effects include anaphylaxis. Doxycycline: Common side effects encompass nausea, vomiting, diarrhea, and photosensitivity (sunburn). Long-term use may lead to tooth discoloration in children and esophageal irritation.
Drug Interactions
Amoxicillin: May interact with anticoagulants (blood thinners) and some contraceptives. Doxycycline: Interacts with antacids, dairy products, and some medications, including warfarin (anticoagulant) and certain antibiotics.
Specific Infections
Contraindications and Precautions
Both drugs have contraindications. Amoxicillin should be avoided by those with penicillin allergies. Doxycycline is generally not recommended for pregnant or breastfeeding women, or children under 8 years old due to potential tooth discoloration. Always discuss your medical history with your doctor before starting either antibiotic.
