What are the side effects of doxycycline (antibiotic)?

Side Effects of Doxycycline

Doxycycline commonly causes gastrointestinal disturbances, photosensitivity, and esophagitis, with more serious but rare adverse effects including hepatotoxicity, dermatological reactions, and neurological complications. 1, 2

Common Side Effects

Gastrointestinal Effects

• Nausea, vomiting, diarrhea (15.7% vs 5.9% with placebo) 1
• Dysphagia and abdominal discomfort 1
• Esophagitis and esophageal ulcerations (especially when taken immediately before lying down) 2
• Risk factors for GI side effects:
  • Age ≥50 years (significantly higher incidence) 3
  • Higher dosage (200 mg/day vs 100 mg/day) 3

Dermatological Effects

• Photosensitivity reactions (increased risk of sunburn) 1, 2
• Rash 1
• Photo-onycholysis (separation of nail from nail bed due to light exposure) 1

Serious but Rare Side Effects

Dermatological Reactions

• Exfoliative dermatitis 1
• Erythema multiforme 1, 2
• Stevens-Johnson syndrome 1, 2
• Toxic epidermal necrolysis 1, 2

Hepatic Effects

• Hepatitis and jaundice 1
• Hepatic failure (rare) 1
• Elevated liver enzymes 4

Hematological Effects

• Hemolytic anemia 1, 2
• Thrombocytopenia 1, 2
• Neutropenia 1
• Eosinophilia 1, 2

Neurological Effects

• Benign intracranial hypertension (pseudotumor cerebri) 1, 2
• Bulging fontanels in infants 2

Immunological Effects

• Anaphylaxis 1
• Serum sickness-like reactions 1, 2
• Exacerbation of systemic lupus erythematosus 1, 2

Renal Effects

• Renal dysfunction (lower risk with doxycycline than other tetracyclines) 1
• Rise in blood urea nitrogen (dose-related) 2

Infectious Complications

• Pseudomembranous colitis (Clostridioides difficile-associated diarrhea) 1, 2
• Candida vulvovaginitis 1

Risk Minimization Strategies

For Gastrointestinal Side Effects

• Take doxycycline with food and a full glass of water 1
• Remain upright for at least 1 hour after taking the medication 1
• Consider enteric-coated formulations which show better GI tolerability 5

For Photosensitivity

• Avoid direct exposure to sunlight or UV irradiation 1
• Use sunscreen and protective clothing when outdoors 1
• Discontinue treatment at first evidence of skin erythema 2

Drug Interactions to Avoid

• Separate doxycycline dose by at least 2-3 hours from:
  • Aluminum, calcium, or magnesium-containing antacids 1
  • Iron-containing preparations 1
  • Dairy products 1
  • Supplements containing calcium, iron, magnesium, or sodium bicarbonate 1

Monitoring Recommendations

• Routine toxicity monitoring tests (complete blood count, kidney function, liver function) should be performed intermittently throughout treatment 1, 4
• Monitor for signs of esophagitis and esophageal ulceration, especially in patients taking capsule or tablet forms immediately before bedtime 2
• Assess for photosensitivity reactions, particularly during summer months or in sunny climates 4

Contraindications

• Hypersensitivity to doxycycline or other tetracyclines 1
• Children under 8 years of age (risk of permanent teeth discoloration and enamel hypoplasia) 1, 2
• Pregnancy and breastfeeding 1

Doxycycline is generally well-tolerated when proper administration guidelines are followed, with most studies reporting low discontinuation rates (2.6-4%) due to adverse effects 3, 6, 7.