What are the dosage instructions and potential side effects of doxycycline?

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Last updated: August 20, 2025View editorial policy

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Patient Education for Doxycycline

Take doxycycline 100 mg twice daily with a full glass of water, remain upright for at least 30 minutes afterward, and avoid dairy products, antacids, or supplements containing calcium, iron, or magnesium within 2 hours of taking the medication to ensure proper absorption. Common side effects include photosensitivity (increased sun sensitivity), nausea, diarrhea, and esophageal irritation, so use sunscreen, take with food if stomach upset occurs, and contact your healthcare provider if you experience severe side effects or symptoms don't improve after completing treatment.

Dosage Instructions

  • Take doxycycline exactly as prescribed (typically 100 mg twice daily for 7 days for most infections) 1
  • Take with a full glass of water to prevent esophageal irritation 2
  • Remain upright (sitting or standing) for at least 30 minutes after taking to prevent esophageal ulceration 2
  • May take with food if stomach upset occurs, though this is not required for absorption 1

Important Precautions

  • Avoid taking within 2 hours of:
    • Antacids containing aluminum, calcium, or magnesium
    • Iron supplements
    • Calcium supplements
    • Dairy products
    • Products containing sodium bicarbonate 2, 1
  • Use sunscreen and protective clothing as doxycycline can cause increased sensitivity to sunlight 3
  • Complete the entire course of medication even if symptoms improve before finishing 2
  • Avoid pregnancy during treatment as doxycycline is pregnancy category D 3, 1
  • May reduce effectiveness of hormonal contraceptives; consider additional contraception 1

Potential Side Effects

  • Common side effects include:

    • Nausea, vomiting, diarrhea
    • Esophageal irritation
    • Photosensitivity (increased sun sensitivity)
    • Vaginal yeast infections 3, 1
  • Rare but serious side effects requiring immediate medical attention:

    • Severe skin reactions
    • Difficulty swallowing
    • Severe headache or vision changes
    • Allergic reactions 3

Contact your healthcare provider if symptoms worsen or don't improve after completing treatment, or if you experience severe side effects.

References

Guideline

Antibiotic Treatment Guidelines

Praxis Medical Insights: Practical Summaries of Clinical Guidelines, 2025

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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