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Doxycycline hyclate tablets 20mg


Tablets containing doxycycline hyclate.

Drugs List

  • doxycycline 20mg tablets
  • PERIOSTAT 20mg tablets
  • Therapeutic Indications


    Periodontitis -chronic adult



    The recommended dosage is 20mg twice a day for a three month period.

    No more than 3 consecutive three month periods.


    Children aged 12 to 18 years: No dosage adjustment required. See Dosage; Adults.

    Doxycycline is contraindicated in children up to 12 years.

    Patients with Hepatic Impairment

    Doxycycline should be administered with caution to patients with hepatic impairment. There are no data, at the time of writing, to support the safety of doxycycline in hepatic impairment at the recommended doses.


    Children under 12 years

    Precautions and Warnings

    History of oral candidiasis
    Glucose-galactose malabsorption syndrome
    Hepatic impairment
    Lactose intolerance
    Myasthenia gravis
    Systemic lupus erythematosus

    Jarisch-Herxheimer reaction possible in treatment of Spirochetes infection
    May exacerbate myasthenia gravis
    Advise ability to drive/operate machinery may be affected by side effects
    Contains lactose
    Swallow dose with plenty of fluid while sitting or standing
    Monitor periodically for overgrowth of non-susceptible organisms
    Consider pseudomembranous colitis if patient presents with diarrhoea
    Discontinue treatment immediately if signs of phototoxicity occur
    Prolonged use may result in superinfection with non-susceptible organisms
    Discontinue at first signs of skin erythema
    Discontinue if benign intracranial hypertension develops
    Discontinue if overgrowth of resistant organisms occurs
    Discontinue if severe hypersensitivity reactions occur
    Advise avoid milk/antacid/mineral supplements 2 hours before or after dose
    Advise patient not to take St John's wort concurrently
    Advise patient that photosensitivity possible
    Advise patient to avoid exposure to sunlight and UV rays during treatment
    Advise patient to avoid taking immediately before going to bed

    Doxycycline should be used with care in patients with a history of or predisposition to oral candidosis. The safety and efficacy of doxycycline has not been established for the treatment of periodontitis in patients with co-existent oral candidosis. There is a possibility that the use of tetracyclines may increase the incidence of vaginal candidosis.

    Doxycycline therapy may result in overgrowth of non-susceptible micro-organisms including fungi (with clinical symptoms of persistent bad breath, reddening of the gums etc.). Monitoring periodically for overgrowth of non-susceptible organisms is essential. Doxycycline has been associated with diarrhoea, colitis, vaginal moniliasis which may suggest over-growth of non-susceptible micro-organisms. Discontinue if overgrowth of resistant organisms occurs and treat appropriately.

    Pregnancy and Lactation


    Doxycycline is contraindicated in pregnancy.

    Studies in animals have not demonstrated a teratogenic effect but have shown effects on skeletal development when given in the first trimester.

    Limited human studies have not revealed any specific malformation. Administration of tetracyclines during the second or third trimester may cause discolouration of the child's teeth. The risks are predominantly associated with the effects on teeth and skeletal development. Enamel hypoplasia has been reported.

    Schaefer (2015) suggests that the use of tetracyclines be contraindicated beyond the fifteenth week of gestation. If used after the fifteenth week this is not an indication for termination of pregnancy or for invasive prenatal diagnostic procedures.



    Doxycycline is excreted in human breast milk.

    Hale suggests prolonged use whilst breastfeeding may induce dental staining and alter gastrointestinal flora of the nursing infant.


    Advise patient the tablets should be taken with adequate fluid (at least 100ml of water) in a sitting or standing position to avoid oesophageal irritation or ulceration.

    Advise patient tablets should be taken at least one hour before meals and the evening dose should be taken well before retiring to minimise the risks of oesophageal irritation and ulceration.

    Advise patient to avoid milk, antacids and mineral supplements for 2 hours before or after dose.

    Advise patient to avoid taking St John's wort concurrently.

    Advise patient to avoid excessive sunlight or artificial ultra-violet light and to consider using sunscreen or sunblock.

    Patient should be advised not to drive or operate machinery if affected by side effects such as nausea and dizziness.

    Side Effects

    Abdominal pain
    Accidental injury
    Anaphylactoid purpura
    Angioneurotic oedema
    Anogenital candidiasis
    Antibiotic-associated colitis
    Back pain
    Benign intracranial hypertension
    Blood urea increased
    Brown-black microscopic discolouration of thyroid tissue
    Bulging fontanelles in infants
    Common cold
    Diarrhoea - bloody
    Dry mouth
    Enamel hypoplasia
    Exfoliative dermatitis
    Haemolytic anaemia
    Hypersensitivity reactions
    Influenza-like symptoms
    Jarisch-Herxheimer reaction
    Joint pain
    Maculopapular rash
    Menstrual discomfort
    Muscle pain
    Oesophageal ulceration
    Opportunistic infections
    Periodontal abscess
    Pseudomembranous colitis
    Sinus headache
    Sore gums
    Sore throat
    Staining of teeth
    Stevens-Johnson syndrome
    Tooth ache
    Tooth disorder
    Vaginal candidiasis
    Worsening of lupus erythematosus


    It is strongly recommended that the UK National Poisons Information Service be consulted on cases of suspected or actual overdose where there is doubt over the degree of risk or about appropriate management.

    The following number will direct the caller to the relevant local centre (0844) 892 0111

    Information may be obtained if you have access to ToxBase the primary clinical toxicology database of the National Poisons Information Service. This is available via password on the internet ( ) or if this is unavailable at the backup site ( ).

    Further Information

    Last Full Review Date: April 2019

    Reference Sources

    Drugs During Pregnancy and Lactation: Treatment Options and Risk Assessment, 3rd edition (2015) ed. Schaefer, C., Peters, P. and Miller, R. Elsevier, London.

    Drugs in Pregnancy and Lactation: A Reference Guide to Fetal and Neonatal Risk, 10th edition (2015) ed. Briggs, G., Freeman, R. Wolters Kluwer Health, Philadelphia.

    NICE Evidence Services Available at: Last accessed: 07 March 2019

    Summary of Product Characteristics: Periostat 20mg film-coated tablets. Alliance Pharmaceuticals. Revised November 2017.

    The Welsh Medicines Information Centre (WMIC) Porphyria Information Service.
    Available at:
    Last revised: April 2018
    Last accessed: 07 March 2019

    The Norwegian Porphyria Centre (NAPOS).
    Available at:
    Last revised: 22 September 2018
    Last accessed: 07 March 2019

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