C. diff Risk


Oral Bioavailability


Approximate Cost



100 mg PO q12h

General (including Lyme Disease)

8+ Years: 4 mg/kg/24h PO divided q12h
Maximum: 200 mg/24h
Doxycycline is not usually recommended in children less than 8 years of age. However consideration should be given to using doxycycline in persons under 8 years of age if it is optimal therapy for specific infections. Infectious Diseases consultation can be obtained to discuss the issues. (example lyme facial palsy, see Lyme guidelines)
Not recommended for greater than 21 days in children less than 8 years of age as there are limited safety data.

General Information

Common Usage

  • Lyme disease

  • Skin and soft tissue infection

  • Methicillin resistant staphylococcus aureus infections

Adverse Effects

  • GI upset (take with food to avoid)

  • Erosive esophagitis (drink plenty of water with dose)

  • Photosensitivity rash

  • Teeth staining (risk much lower than with other tetracyclines)

Major Interactions

Divalent cations- decreased absorption therefore recommended to space by 2 hours.

Tablet/Capsule Strengths

100 mg tablet (scored in quarters)
Tablets and capsules are preferred especially over an unpleasant tasting liquid.
Not all strengths of oral tablets/capsules are listed and they are not all available on the IWK formulary

Additional Information

Take with food to reduce GI upset.
Avoid iron, magnesium, calcium for at least two hours before or two hours after doxycycline administration.

Contraindicated in pregnancy and not routinely recommended in children <8 years of age due to risk for tooth enamel hypoplasia and permanent discolouration of the developing teeth (much lower than other tetracyclines)


Antimicrobial class: Tetracycline

Average serum half life: No data for pediatrics.
Adults: 12 to 15 hours (usually increases to 22 to 24 hours with multiple dosing)

Route of Elimination: In the urine (23%) and feces (30%)