Doxycycline is a versatile, second-generation tetracycline-class antibiotic renowned for its broad-spectrum efficacy against a wide array of bacterial pathogens. It functions by inhibiting protein synthesis, effectively halting bacterial growth and proliferation. This medication is a cornerstone in treating numerous infections, from common respiratory ailments to complex tropical diseases, and is valued for its generally favorable tolerability profile and convenient dosing regimen.

Features

• Active Ingredient: Doxycycline (as doxycycline hyclate or monohydrate)
• Drug Class: Tetracycline antibiotic
• Available Forms: Oral tablets, capsules, and suspension; intravenous injection
• Typical Strengths: 50 mg, 75 mg, 100 mg, 150 mg
• Mechanism of Action: Binds to the 30S ribosomal subunit, inhibiting bacterial protein synthesis
• Spectrum of Activity: Effective against Gram-positive, Gram-negative, atypical, and some parasitic organisms

Benefits

• Effectively treats a diverse range of bacterial infections, reducing symptom duration and severity.
• Offers convenient once or twice-daily dosing, improving patient adherence to treatment regimens.
• Demonstrates high tissue penetration, reaching effective concentrations at sites of infection.
• Can be used for both treatment and prophylaxis of specific infections, including malaria.
• Generally well-tolerated with a established safety profile when used appropriately.

Common use

Doxycycline is indicated for the treatment of infections caused by susceptible strains of microorganisms, including but not limited to: Rocky Mountain spotted fever, typhus fever, Q fever, respiratory tract infections (e.g., pneumonia, bronchitis), urinary tract infections, sexually transmitted infections (e.g., chlamydia, gonorrhea, syphilis), skin and soft tissue infections, anthrax (inhalational and cutaneous), acne vulgaris, malaria prophylaxis, and ocular infections. Its anti-inflammatory properties also make it useful in managing rosacea and periodontitis.

Dosage and direction

Dosage varies significantly based on the infection being treated, patient age, renal function, and formulation. For adults, typical doses range from 100 mg to 200 mg daily, administered as a single dose or in divided doses (every 12 hours). For severe infections, an initial loading dose of 200 mg may be administered. Pediatric dosing (>8 years) is typically 2-4 mg/kg/day in divided doses. Administration with a full glass of water is imperative to reduce esophageal irritation and ulceration. To maximize absorption and minimize gastrointestinal upset, it should be taken with food or milk, though dairy products can impair absorption if consumed simultaneously; a separation of at least 2 hours is recommended. Do not lie down for at least 30 minutes after taking a dose.

Precautions

Patients should be advised to avoid excessive sunlight or artificial UV light (tanning beds) due to photosensitivity reactions. Use with caution in patients with hepatic impairment. May cause esophageal irritation; ensure adequate fluid intake with dosing. As with all antibiotics, doxycycline may cause Clostridium difficile-associated diarrhea. Use during tooth development (last half of pregnancy, infancy, childhood up to age 8) may cause permanent discoloration of teeth (yellow-gray-brown) and enamel hypoplasia. It is not recommended for the treatment of streptococcal pharyngitis due to high resistance rates.

Contraindications

Hypersensitivity to doxycycline, other tetracyclines, or any component of the formulation. Contraindicated for use in children under 8 years of age (except for serious infections where alternatives are not suitable, such as for anthrax or Rocky Mountain spotted fever).

Possible side effect

Common side effects include nausea, vomiting, diarrhea, photosensitivity, rash, and esophageal irritation. Less frequently, it may cause glossitis, stomatitis, colitis, vaginal candidiasis, and elevated liver enzymes. Rare but serious side effects include intracranial hypertension (presenting as headache and blurred vision), severe skin reactions (e.g., Stevens-Johnson syndrome), and hepatotoxicity. Discoloration of teeth and inhibition of bone growth can occur if used in young children.

Drug interaction

Antacids containing aluminum, calcium, or magnesium; iron preparations; bismuth subsalicylate; and zinc can significantly decrease doxycycline absorption. Barbiturates, carbamazepine, and phenytoin may decrease doxycycline levels. Doxycycline may potentiate the effect of warfarin, necessitating closer INR monitoring. Concurrent use with isotretinoin should be avoided due to increased risk of intracranial hypertension. It may reduce the efficacy of oral contraceptives; advise use of an alternative non-hormonal contraceptive method.

Missed dose

If a dose is missed, it should be taken as soon as remembered. However, if it is almost time for the next scheduled dose, the missed dose should be skipped. Do not double the dose to make up for a missed one.

Overdose

Symptoms of overdose are primarily extensions of common side effects, notably severe nausea, vomiting, and diarrhea. There is no specific antidote. Management is supportive and symptomatic, including gastric lavage if ingestion was recent. Not removed by hemodialysis.

Storage

Store at room temperature (20°C to 25°C or 68°F to 77°F), in a tight, light-resistant container. Keep away from moisture, light, and excessive heat. Keep all medications out of the reach of children and pets.

Disclaimer

This information is for educational purposes only and does not constitute medical advice. It is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition or before starting any new treatment. Never disregard professional medical advice or delay in seeking it because of something you have read here.

Reviews

“Doxycycline was prescribed for a persistent respiratory infection after other antibiotics failed. Noticeable improvement within 48 hours. The once-daily dosing was convenient, though I experienced mild photosensitivity, so sunscreen was essential.” – Verified Patient

“As a physician, I find doxycycline to be an invaluable tool, particularly for treating atypical pneumonias and for malaria prophylaxis in travelers. Its broad spectrum and generally predictable pharmacokinetics make it a reliable choice, though patient counseling on sun avoidance is critical.” – Medical Professional

“Effective for managing my moderate inflammatory acne. It took several weeks to see full results, but the reduction in redness and number of breakouts was significant. Experienced some initial stomach upset that subsided.” – Verified Patient