Doxycycline is a widely used antibiotic that belongs to the tetracycline class. It is known for its effectiveness against a variety of bacterial infections.

What is Doxycycline?

Doxycycline is a broad-spectrum antibiotic, meaning it is effective against a wide range of bacteria. It works by inhibiting the production of proteins that bacteria need to grow and multiply. This action helps the body’s immune system to eliminate the infection.

Uses of Doxycycline

Doxycycline is prescribed for several types of infections, including:

  1. Respiratory Infections: It treats pneumonia, bronchitis, and sinusitis caused by bacteria.
  2. Urinary Tract Infections (UTIs): Effective against bacteria that cause UTIs.
  3. Sexually Transmitted Infections (STIs): Used for treating chlamydia, gonorrhea, and syphilis.
  4. Skin Conditions: Acne and rosacea are often treated with doxycycline due to its anti-inflammatory properties.
  5. Malaria Prevention: Taken as a prophylactic measure in areas where malaria is prevalent.
  6. Anthrax: Part of the treatment regimen for anthrax exposure.

How Does Doxycycline Work?

Doxycycline inhibits the synthesis of proteins that bacteria require to grow and reproduce. It binds to the 30S ribosomal subunit of the bacteria, preventing the addition of amino acids to the growing protein chain. This action stops bacterial growth and allows the immune system to eliminate the infection.

Dosage and Administration

Doxycycline is available in several forms, including tablets, capsules, and liquid suspensions. The dosage varies depending on the infection being treated:

  • Adults: Typically, the dose ranges from 100 mg to 200 mg per day.
  • Children: Dosage is based on body weight, usually 2.2 mg to 4.4 mg per kg of body weight per day.

It is essential to take doxycycline exactly as prescribed by a healthcare professional. It should be taken with a full glass of water and not lying down for at least 30 minutes to prevent irritation of the esophagus.

Side Effects of Doxycycline

Like all medications, doxycycline can cause side effects. Common side effects include:

  • Gastrointestinal Issues: Nausea, vomiting, diarrhea, and loss of appetite.
  • Skin Reactions: Sensitivity to sunlight (photosensitivity), which can cause severe sunburn.
  • Allergic Reactions: Rash, itching, swelling, and difficulty breathing in severe cases.

Rare but serious side effects can include:

  • Intracranial Hypertension: Increased pressure in the brain, which can cause headaches, blurred vision, and, in severe cases, permanent vision loss.
  • Liver Damage: Symptoms include jaundice, dark urine, and severe abdominal pain.

Precautions and Interactions

Before taking doxycycline, inform your healthcare provider if you have any of the following conditions:

  • Allergies: To doxycycline or other tetracycline antibiotics.
  • Pregnancy and Breastfeeding: Doxycycline is not recommended during pregnancy and breastfeeding due to the risk of harm to the fetus and infant.
  • Liver or Kidney Disease: Dose adjustments may be necessary.

Doxycycline can interact with other medications, including:

  • Antacids and Supplements: Products containing calcium, magnesium, aluminum, or iron can reduce the effectiveness of doxycycline.
  • Blood Thinners: May increase the risk of bleeding.
  • Other Antibiotics: Can interfere with the effectiveness of doxycycline.


Doxycycline is a versatile antibiotic with a broad range of uses, from treating bacterial infections to preventing malaria. While it is generally well-tolerated, it is essential to follow the prescribed dosage and be aware of potential side effects and interactions. Always consult with a healthcare professional before starting any new medication.