What is Doxycycline?

Doxycycline is an active ingredient used for the treatment of pneumonia, severe acne vulgaris, malaria caused by Plasmodium falciparum resistant to chloroquine, and other infections (urethritis, cervicitis, donovanosis, brucellosis, etc.). The product ingredienst are: Doxycycline calcium, Doxycycline hyclate, Doxycycline hydrochloride (hcl), Doxycycline monohydrate.

The brand names of Doxycycline in the United States are: Vibramycin, Monodox, Oracea, Adoxa.

Doxycycline Mechanism of Action (MOA)

Bacteriostatic. Inhibitor of bacterial protein synthesis by binding to ribosomal subunit 30S.

Therapeutic indications, uses and benefits of Doxycycline

Treatment of the following infections caused by sensitive microorganisms: atypical pneumonia caused by Mycoplasma pneumoniae and Chlamydia pneumoniae; psittacosis; uncomplicated urethritis, cervicitis and non-gonococcal proctitis; venereal lymphogranuloma; inguinal granuloma (donovanosis); pelvic inflammatory disease; primary and secondary stages of syphilis, as well as late and latent syphilis, in patients allergic to penicillin; acute orquiepidimitis; trachoma; Inclusion conjunctivitis; infections caused by rickettsias such as Rocky Mountain spotted fever, Mediterranean fever, typhus (endemic and weed typhus) and Q fever; brucellosis (in combination with streptomycin); cholera; Lyme disease (initial stages 1 and 2); recurrent fevers transmitted by lice and ticks; malaria caused by Plasmodium falciparum resistant to chloroquine.

Alternative treatment in: anthrax (cutaneous, intestinal or pulmonary), tularemia, listeriosis, bartonellosis and actinomycosis.

Adjuvant in the treatment of severe acne vulgaris.

Prophylaxis of: malaria caused by Plasmodium falciparum in areas with resistance to mefloquine or when other antimalarials cannot be used in areas with resistance to chloroquine and post-exposure prophylaxis to Bacillus anthracis, as an alternative to quinolones.
Modified release forms: reduce papulopustular lesions in adults. with facial rosacea.

Dosage of Doxycycline

1) Adults and children over 8 years of age with body weight > 45 kg. First day: 200 mg in single dose or 100 mg/12 h; maintenance: 100 mg/24 h, severe infection: 100 mg/12 h.

– Intravenous.
Urethritis, cervicitis and uncomplicated non gonococcal proctitis and orquiepidimitis: administer together with ceftriaxone.
Brucellosis: administer with streptomycin.
PID: in patients requiring hospitalization administer 100 mg/12 h, together with cephalosporin (cefoxitin) IV at least 4 days and at least until 24-48 h after observing the patient’s improvement; continue with 100 m/12 h orally. Duration of treatment: 14 days.
Cholera: 300 mg as a single dose.
Cutaneous, intestinal or pulmonary anthrax: initial, 100 mg/12 h IV followed by the same oral dose when considered appropriate; duration of treatment: 60 days, except in cutaneous anthrax without systemic compromise, which will be 7-10 days.

– Oral.
The initial dose is usually 100 mg every 12 hours or per day depending on the disease to be treated.
Cholera: 300 mg. Single dose
Treatment of P. falciparum malaria resistant to chloroquine: 200 mg/day. For at least 7 days.
Severe acne: Dose 50-100 mg/day.

Modified release forms. Adults, including elderly patients: 40 mg/day.

2) Children over 8 years of age with body weight less than 45 kg. First day: 4.4 mg/kg in a single dose or 2.2 mg/kg/12 h; maintenance: 2.2 mg/kg/24 h.

Severe infection: 4.4 mg/kg/24 h.
Treatment of cutaneous, intestinal or pulmonary anthrax: 2.2 mg/kg/12 h IV followed by the same oral dose 2 times/day, 60 days (reduce duration to 7-10 days in cutaneous anthrax without systemic compromise and consider the use of 2 antibiotics in association with pulmonary anthrax).
Malaria prophylaxis: 2 mg/kg in a single dose/day (without surpassing that of adults), 1-2 days before the trip, during and 4 weeks after the trip.

Mode of administration of Doxycycline

Oral use.
Always take during a meal, accompanied by a glass of water (200 ml) or with milk and allowing at least 1 hour to elapse before lying down or going to bed, to avoid possible esophageal irritation.

For modified release forms: take in the morning on an empty stomach, preferably at least 1 h before or 2 h after a meal. It should be taken with an adequate amount of water to reduce the risk of irritation and esophageal ulcer.

Intravenous (IV) injectable forms: do not administer intramuscularly or subcutaneously. Use extreme caution during administration to avoid depositing the IV solution in adjacent tissues.
Rapid administration should be avoided.
Bolus administration: inject slowly (no less than 2 min to administer each 100 mg dose).
Administration in perfusion: maximum speed of perfusion is 100 mg/h.

Contraindications of Doxycycline

  • Hypersensitivity to doxycycline or other tetracyclines.
  • Concomitant treatment with methoxyflurane (reported cases of renal toxicity with fatal result).
  • Also in injectable forms: patients with myasthenia gravis. Also for modified release forms:
  • Babies and children ≤ 12 years.
  • Second and third trimester of pregnancy.
  • Concomitant treatment with oral retinoids.
  • Patients with achlorhydria or who have undergone surgery to avoid (by-pass) or remove the duodenum.

Warnings and Precautionsof Doxycycline

  • Do not use, except in the case of children < 8 years old.
  • Second half of pregnancy and lactation (possible permanent tooth colouring, hypoplasia of the enamel and reversible alteration of bone growth).
  • Monitor overinfection by resistant microorganisms.
  • Caution in patients with: history of predisposition to develop candidiasis, myasthenia gravis, hepatic alterations or in concomitant treatment with hepatotoxic drugs, perform hematological control and hepatic and renal functions (possible increase of BUN).
  • Risk of: diarrhea associated with Clostridium difficile, pseudomembranous colitis, photosensitivity (discontinue treatment if erythema cutaneous).
  • May cause transient benign intracranial hypertension (pseudotumor cerebri).
  • Perform ophthalmic evaluations.
  • Avoid concomitant treatment with isotretinoin.
  • May cause fontanel bulging in children, reversible.
  • Avoid systemic lupus erythematosus.
  • In group A ß-hemolytic streptococcus infection, administer min. 10 days; solid oral forms: administer with food and do not lie down in min. 1 h, risk of esophageal damage.
  • Do not use in ocular manifestations of rosacea (such as ocular rosacea and/or blepharitis/meibomianitis).

Liver failure

Control liver function.

Kidney failure

Control kidney function, possible increase in BUN.

Interactions with Doxycycline

  • Reduces the effect of: oral contraceptives.
  • Potency action of: oral anticoagulants (reduce dose), oral anti-diabetics of the sulfonylurea type (monitor and adjust dose), isotretinoin (risk of increased intracranial hypertension), avoid.
  • Interferes with bactericidal action of: penicillin, avoid.
  • Reduced absorption by: Al, Zn, Ca, Mg (in antacids or quinapril), prepared with Fe, activated charcoal, cholestyramine, bismuth chelates and sucralfate (space 2-3 h).
  • Metabolism activated by: rifampicin, barbiturates, carbamazepine, diphenylhydantoin, primidone, phenytoin and alcohol.
  • Increased nephrotoxicity with: diuretics, methoxyflurane.
  • Increases plasma concentration of: lithium, digoxin and theophylline.
  • Incompatible with: sun. Ringer-lactato, bactericidal antibiotics.
  • Lab: false + catecholamines (interferes with fluorescence test) and glucose in urine.

Pregnancy and Doxycycline

Contraindicated during the second and third trimester, it produces a permanent coloration of the definitive teeth of the descendants.


Breastfeeding should be discontinued during treatment with this medication, as tetracyclines, including doxycycline, have been observed to be excreted in breast milk.
For modified release forms: Low levels of tetracyclines are secreted in breast milk.
Doxycycline may be used during lactation only for a short period.
Prolonged use of doxycycline may result in significant absorption by the infant and is therefore not recommended because of the potential risk of tooth discolouration and decreased bone growth in the infant.

Effects on driving ability

No studies have been conducted on the ability to drive and use machines.
There is no evidence to suggest that doxycycline may affect these abilities.

Adverse reactions and side effects of doxycycline

Anaphylactic reaction (including angioedema, exacerbation of systemic lupus erythematosus, pericarditis, hypersensitivity.
Serum disease; Schönlein-Henoch purpura, hypotension, dyspnea, tachycardia, peripheral edema and urticaria).
Headache; nausea, vomiting.
Photosensitivity reaction, eruption including erythematous and maculopapular eruption.

Modified release forms: nasopharyngitis, sinusitis, fungal infection; anxiety; sinusoidal headache; hypertension; diarrhea; upper abdominal pain; dry mouth; back pain; pain at the injection site; ASAT; high blood pressure, LDH and blood glucose. In addition: Jarisch-Herxheimer reaction.


Source: The content of this active ingredient has been written taking into account the clinical and molecular information of all medicines authorised and marketed in the United States under the Unique Ingredient Identifier (UNII) by the Substance Registration System (SRS) of the Food and Drug Administration (FDA) and the United States Pharmacopeia (USP).

In order to know in detail the information authorized by the FDA for each drug, you should consult the corresponding medication guide authorized by the FDA.


NCI Thesaurus: C457

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