| The following adverse reactions have been observed in patients receiving tetracyclines, including doxycycline.Autonomic nervous system Flushing.Body as a whole Hypersensitivity reactions, including anaphylactic shock, anaphylaxis, anaphylactoid reaction, anaphylactoid purpura, hypotension, pericarditis, angioneurotic oedema, exacerbation of systemic lupus erythematosus, dyspnoea, serum sickness, peripheral oedema, tachycardia and urticaria.Central and Peripheral nervous system Headache. Bulging fontanelles in infants and benign intracranial hypertension in juveniles and adults have been reported in individuals receiving full therapeutic dosages of tetracyclines. In relation to benign intracranial hypertension, symptoms included blurring of vision, scotomata and diplopia. Permanent visual loss has been reported.Gastro-intestinal Gastro-intestinal symptoms are usually mild and seldom necessitate discontinuation of treatment. Abdominal pain, anorexia, nausea, vomiting, diarrhoea, dyspepsia and rarely dysphagia. Oesophagitis and oesophageal ulceration have been reported in patients receiving Vibramycin. A significant proportion of these occurred with the hyclate salt in the capsule form. (See 'Special warnings and precautions for use' section).Hearing/Vestibular Tinnitus.Haemopoietic Haemolytic anaemia, thrombocytopenia, neutropenia, porphyria, and eosinophilia have been reported with tetracyclines.Liver/Biliary Transient increases in liver function tests, hepatitis, jaundice, hepatic failure and pancreatitis have been reported rarely.Musculo-Skeletal Arthralgia and myalgia.Skin Rashes including maculopapular and erythematous rashes, exfoliative dermatitis, erythema multiforme, Steven-Johnson syndrome and toxic epidermal necrolysis. Photosensitivity skin reactions (see 'Special warnings and precautions for use' section).Superinfection As with all antibiotics, overgrowth of non-susceptible organisms may cause candidiasis, glossitis, staphylococcal enterocolitis, pseudomembranous colitis (with Clostridium difficile overgrowth) and inflammatory lesions (with candidal overgrowth) in the anogenital region. Similarly there have been reports for products in the tetracycline class of stomatitis and vaginitis.Urinary system Increased blood urea. (See 'Special warnings and precautions for use' section.) Other When given over prolonged periods, tetracyclines have been reported to produce brown-black microscopic discolouration of thyroid tissue. No abnormalities of thyroid function are known to occur. Tetracyclines may cause discoloration of teeth and enamel hypoplasia, but usually only after long-term use. | |