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Pronunciation: DOX-ee-SIGH-kleen
Class: Antimalarial preparation, Mouth and throat product, Tetracycline

Trade Names

- Capsules 150 mg (as monohydrate)
- Tablets 50 mg (as monohydrate)
- Tablets 75 mg (as monohydrate)
- Tablets 100 mg (as monohydrate)

- Tablets, delayed release 150 mg (as hyclate)

Doxycycline Hyclate
- Capsules, delayed-release 100 mg
- Tablets 100 mg
- Tablets, delayed release 75 mg
- Tablets, delayed release 100 mg
- Capsules 50 mg
- Injection, lyophilized powder for solution 100 mg

Doxycycline Monohydrate
- Capsules 50 mg
- Tablets 150 mg

- Capsules 100 mg (as hyclate)

- Capsules 75 mg (as monohydrate)
- Capsules 100 mg (as monohydrate)

- Capsules 75 mg (as monohydrate)

- Capsules, delayed release 40 mg

- Capsules 20 mg (as hyclate)

- Tablets 20 mg (as hyclate)

- Capsules 100 mg (as hyclate)
- Powder for oral suspension 25 mg (as monohydrate) per 5 mL when reconstituted
- Syrup 50 mg per 5 mL (as calcium)

Apo-Doxy (Canada)
Apo-Doxy-Tabs (Canada)
Doxycin (Canada)
Nu-Doxycycline (Canada)


Inhibits bacterial protein synthesis.

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Well absorbed. T max is 2 to 2.6 h (oral). C max is 2.6 mcg/mL (200 mg oral hyclate dose), 2.5 to 3.6 mcg/mL (100 to 200 mg IV dose). Absorption may be decreased by 20% when given with food or milk.


Bound to plasma proteins. Crosses the placenta; excreted in breast milk.


Approximately 40% excreted by the kidneys in 72 h. The t ½ is 16 to 22 h.

Special Populations

Renal Function Impairment

Excretion by the kidneys may fall as low as 1% to 5% in 72 h in those with Ccr less than 10 mL/min.

Indications and Usage

Treatment of infections caused by susceptible strains of gram-positive and gram-negative bacteria (eg, Rickettsia , Mycoplasma pneumoniae ); treatment of trachoma and susceptible infections when penicillins are contraindicated; treatment of acute intestinal amebiasis; uncomplicated gonorrhea in adults; prophylaxis of malaria caused by Plasmodium falciparum ; anthrax (including inhalational anthrax); severe acne; treatment of only inflammatory lesions of rosacea ( Oracea only); adjunct treatment to scaling and root planing to promote attachment level gain and reduce pocket depth ( Periostat only).


Hypersensitivity to tetracyclines; nursing mothers, infants, and children ( Periostat ).

Dosage and Administration

Acute Epididymo-Orchitis Caused by Neisseria Gonorrhoeae or Chlamydia Trachomatis

PO 100 mg twice daily for at least 10 days.

Chlamydia Infections
Adults and Children 8 y of age and older

PO 100 mg twice daily for 7 days.

Epididymitis Most Likely Caused by Gonococcal or Chlamydial Infection

PO 100 mg twice daily for 10 days plus a single dose of 250 mg ceftriaxone IM.

Adults and children older than 8 y of age and weighing more than 45 kg

PO 200 mg on the first day (100 mg every 12 h) then 100 mg/day. For more severe infections (particularly chronic UTI), administer 100 mg every 12 h. In streptococcal infections, continue therapy for 10 days. IV 200 mg on the first day (as 1 or 2 infusions) then 100 to 200 mg/day, depending upon the severity of infections, with 200 mg administered in 1 or 2 infusions.

Children older than 8 y of age and weighing 45 kg or less

PO 4.4 mg/kg divided into 2 doses on day 1 followed by 2.2 mg/kg/day as a single dose or divided into 2 doses on subsequent day. For more severe infections, 4.4 mg/kg may be used. In streptococcal infections, continue therapy for 10 days. IV 4.4 mg/kg on day 1 (in 1 or 2 infusions) followed with 2.2 to 4.4 mg/kg given as 1 or 2 infusions, depending on the severity of the infection.

Lymphogranuloma Venereum and Granuloma Inguinale

PO 100 mg twice daily for at least 21 days.

Malaria Prophylaxis

PO 100 mg daily, beginning 1 to 2 days before travel and continuing for 4 wk after leaving area.

Children older than 8 y of age

PO 2 mg/kg daily up to 100 mg per day. Begin 1 to 2 days before travel and continue for 4 wk after leaving area.

Nongonococcal Urethritis

PO 100 mg twice daily for 7 days.

Pelvic Inflammatory Disease

PO / IV 100 mg every 12 h plus 2 g cefotetan IV every 12 h or 2 g cefoxitin IV every 6 h. Parenteral therapy may be discontinued after 24 h; continue oral therapy with doxycycline for a total of 14 days.

Periodontitis ( Periostat only)

PO 20 mg twice daily as an adjunct following scaling and root planing for up to 9 mo. Administer tablets at least 2 h before or after meals.

Rosacea ( Oracea only)

PO 40 mg in the morning on an empty stomach, at least 1 h prior to or 2 h after a meal.

Sexual Assault Prophylaxis

PO 100 mg twice daily for 7 days plus ceftriaxone and metronidazole.

Early (except Adoxa , NutriDox , Monodox )

PO 100 mg twice daily for 14 days.

More than 1 y duration (except Adoxa , NutriDox , Monodox )

100 mg twice daily for 28 days.

Primary and secondary ( Adoxa , NutriDox , Monodox )

300 mg/day in divided doses for at least 10 days.

Uncomplicated Gonococcal Infection (Except Anorectal Infections in Men)

PO 100 mg twice daily for at least 7 days. Single visit dose: 300 mg immediately followed with 300 mg in 1 h.

Uncomplicated Urethral, Endocervical, or Rectal Infections Caused by C. Trachomatis

PO 100 mg twice daily for at least 7 days.

Inhalation Anthrax (Post-exposure)
Adults and children (100 lb [45 kg] or more)

PO 100 mg twice daily for 60 days.

Children (less than 100 lb [45 kg])

PO 2.2 mg/kg twice daily for 60 days.

General Advice

  • Oral
  • Administer tablets or capsules with a full glass of water.
  • Doryx tablets may be broken up and the contents sprinkled over applesauce. Do not crush/damage the pellets when breaking up the tablet. Swallow mixture immediately.
  • Shake suspension well before measuring dose.
  • Administer prescribed dose of suspension or syrup using dosing syringe, dosing spoon, or medicine cup.
  • Administer Periostat 2 h before or 2 h after antacids containing aluminum, calcium, or magnesium; preparations containing iron or zinc; or dairy products (eg, milk, cheese, ice cream).
  • Administer other oral doxycycline products 1 h before or 2 h after antacids containing aluminum, calcium, or magnesium, or preparations containing iron or zinc.
  • Injection
  • For IV infusion only.
  • Follow manufacturer's guidelines for reconstituting and further diluting the powder for injection.
  • Do not administer if particulate matter, cloudiness, or discoloration noted.
  • Protect diluted solutions from direct sunlight during storage and infusion.
  • For solutions diluted with lactated Ringers injection or dextrose 5% in lactated Ringers, complete infusion within 6 h of reconstitution. Discard any remaining solution after 6 h.


Store tablets, capsules, syrup, and oral suspension at 59° to 86°F. Store lyophilized powder at or below 77°F. Solutions diluted with other IV infusion solutions may be stored for up to 72 h prior to start of infusion if refrigerated (36° to 46°F) and protected from sunlight and artificial light. Infusion must be completed within 12 h. Discard any remaining solution after 12 h.

Drug Interactions

Antacids (containing aluminum, calcium, or magnesium), bismuth salts, divalent/trivalent cations, zinc salts

May decrease oral absorption of doxycycline.

Barbiturates, carbamazepine, hydantoins

May increase metabolism of and decrease effect of doxycycline.

Cholestyramine, colestipol

May decrease absorption of doxycycline.


May increase digoxin serum levels.

Iron salts

May decrease absorption of doxycycline.


Because the risk of pseudotumor cerebri may be increased, avoid isotretinoin administration shortly before, during, or after doxycycline therapy.


Increased potential for nephrotoxicity exists; do not use together.

Milk and dairy products

Although the effects of milk and dairy products on doxycycline absorption are less than observed with other tetracycline derivatives, avoid the administration of milk or dairy products with all tetracycline derivatives.

Oral contraceptives

May decrease contraceptive efficacy.


May interfere with bactericidal action of penicillins.


Anticoagulant effect may be increased; dose may need to be decreased.

Laboratory Test Interactions

False elevations of urinary catecholamine levels may occur because of interference with fluorescence test.

Adverse Reactions


Dizziness; headache; pseudotumor cerebri (manifested by headache and blurred vision).


Maculopapular and erythematous rashes; exfoliative dermatitis; photosensitivity.


Anorexia; nausea; vomiting; diarrhea; glossitis; dysphagia; enterocolitis; inflammatory lesions (with monilial overgrowth) in anogenital area; abdominal pain or discomfort; bulky loose stools; sore throat.


Increase BUN.


Hemolytic anemia; thrombocytopenia; neutropenia; eosinophilia.




Hypersensitivity (including urticaria, angioneurotic edema, anaphylaxis, anaphylactoid reactions, purpura, pericarditis, exacerbation of SLE).


Bulging fontanels (infants); benign intracranial hypertension (adults).



Review results of culture and sensitivity testing as appropriate. Ensure that CBC, liver enzymes, and renal function are periodically evaluated during prolonged therapy.


Category D .


Excreted in breast milk.


Not recommended in children younger than 8 y of age; abnormal bone formation and tooth discoloration may result; not recommended for use in children ( Oracea )

Renal Function

Dosage reduction may be required.

Hepatic Function

Doses greater than 2 g/day associated with liver failure; monitor function and avoid other hepatotoxic drugs.


Prolonged use may result in bacterial or fungal overgrowth.


Photosensitivity may occur; avoid exposure to sunlight or ultraviolet light.

Outdated product

Do not use; degradation products of drug are highly nephrotoxic.

Prolonged IV use

May result in thrombophlebitis; use oral form whenever reasonable.

Special considerations

Doxycycline periodontal injection has not been clinically evaluated for use in the regeneration of alveolar bone, use in immunocompromised patients, or for use in patients with conditions involving extremely severe periodontal defects with very little remaining periodontium.

Patient Information

  • Review dosing schedule and prescribed length of therapy with patient. Advise patient that dose and duration of therapy are dependent on site and cause of infection.
  • Instruct patient using tablets or capsules to take prescribed dose with a full glass of water.
  • Instruct patient or caregiver using syrup or oral suspension to measure and administer prescribed dose using dosing spoon, dosing syringe, or medicine cup.
  • Advise patient to take without regard to meals but to take with food if GI upset occurs.
  • Advise patient using other oral doxycycline products to take 1 h before or 2 h after antacids containing aluminum, calcium, or magnesium, or preparations containing iron or zinc.
  • Instruct patient to complete entire course of therapy, even if symptoms of infection have disappeared.
  • Instruct patient taking doxycycline for malaria prophylaxis to take daily, beginning 1 to 2 days prior to arrival in malaria-infected area, while in the malaria-infected area, and for 28 days after leaving the malaria-infected area. Advise patient that medication is not 100% effective and that protective clothing, insect repellants, and bednets are important components of malaria prophylaxis.
  • Advise patient to discontinue therapy and contact health care provider immediately if skin rash, hives, itching, shortness of breath, headache, or blurred vision occur.
  • Advise patient that medication may cause photosensitivity (sensitivity to sunlight) and to avoid unnecessary exposure to sunlight or tanning lamps and to use sunscreens and wear protective clothing to avoid photosensitivity reactions.
  • Caution women taking oral contraceptives that doxycycline may make birth control pills less effective and to use nonhormonal forms of contraception during treatment.
  • Caution patient that drug may cause dizziness, light-headedness, or blurred vision and to use caution while driving or performing other hazardous tasks until tolerance is determined.
  • Advise patient to report the following signs of superinfection to health care provider: black “furry” tongue, white patches in mouth, foul-smelling stools, vaginal itching or discharge.
  • Warn patient that diarrhea containing blood or pus may be a sign of a serious disorder and to seek medical care if noted and not treat at home.
  • Advise patient to discard any unused doxycycline by the expiration date noted on the label.
  • Periostat
  • Inform patient that this antibiotic will be taken daily for up to 9 mo to help treat periodontitis.
  • Warn patient that although this is a tetracycline antibiotic, the dose is too small to treat infections and should not be used for that purpose.
  • Instruct patient to take 1 h before or 2 h after meals with a full glass of water.
  • Advise patient to take either 2 h before or 2 h after antacids containing aluminum, calcium, or magnesium, preparations containing iron or zinc, or dairy products (eg, milk, cheese, ice cream).

Copyright © 2009 Wolters Kluwer Health.