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Doxycycline Patient Tips

Medically reviewed on Jul 30, 2017 by C. Fookes, BPharm.

How it works

  • Doxycycline is an antibiotic used to treat a wide range of infections caused by susceptible gram negative, gram positive, anaerobic, and other bacteria.
  • Doxycycline is synthetically derived from oxytetracycline (oxytetracycline was first manufactured in 1950).
  • Doxycycline works by inhibiting bacterial protein synthesis by binding to a ribosomal subunit, preventing amino acids from being linked together. Without proteins, bacteria are unable to function.
  • Doxycycline is bacteriostatic (stops bacteria from reproducing, doesn't necessarily kill them).
  • Doxycycline belongs to the group of medicines known as tetracyclines.


  • Active against a wide range of different gram negative, gram positive, anaerobic, other bacteria, and some parasites (such as Balantidium coli and Entamoeba species).
  • May be used in the treatment of various infections such as those occurring in the respiratory tract, genitourinary area, sinuses, and on the skin; some examples include:
    • Tick-borne infections caused by the Rickettsiae group of bacteria, such as Rocky Mountain Spotted fever and typhus fever
    • Respiratory tract infections such as those caused by
    • Haemophilus influenzae
    • ,
    • Streptococcus pneumoniae
    • , or
    • Mycoplasma pneumoniae
    • Eye or genitourinary infections caused by certain Chlamydia species
    • Chancroid, plague, cholera, campylobacter, and brucellosis
    • Syphilis and uncomplicated gonorrhea.
  • Useful as an adjunctive treatment for acne.
  • May be used as an alternative drug to penicillin when penicillin is contraindicated.
  • Generic doxycycline is available.


If you are between the ages of 18 and 60, take no other medication or have no other medical conditions, side effects you are more likely to experience include:

  • A headache, nausea, dyspepsia, joint or back pain, nasal and sinus congestion, a rash, are the more commonly reported side effects.
  • Some people may find they are more sensitive to the sun while taking doxycycline.
  • Tetracyclines, including doxycycline, form a stable calcium complex in bone-forming tissue. This can affect the growth rate of the fibula in young children and skeletal development in the fetus.
  • Can cause permanent tooth discoloration (typically a yellow-gray-brown staining) or enamel hypoplasia (underdeveloped tooth enamel) if used during critical periods of tooth development, such as the last half of pregnancy or in children aged less than eight years. The risk is greater with long-term use but has been noted after short-term use.
  • Clostridium difficile-associated diarrhea, a severe, persistent diarrhea has been associated with most antibiotics, including doxycycline. Seek medical advice if persistent diarrhea occurs within two months of antibiotic use.
  • Use of antibiotics, such as doxycycline, has been associated with an increased risk of vaginal candidiasis (thrush).
  • Cross-resistance is common - this means that if bacteria are resistant to another type of tetracycline, they will likely be resistant to doxycycline.
  • May not be suitable for some people including pregnant or lactating women and children aged less than eight years.
  • May interact with some drugs including anticoagulants, penicillins, antacids or iron-containing preparations, antiepileptics, and oral contraceptives.

Notes: In general, seniors or children, people with certain medical conditions (such as liver or kidney problems, heart disease, diabetes, seizures) or people who take other medications are more at risk of developing a wider range of side effects. For a complete list of all side effects, click here.

Bottom Line

Doxycycline is an effective antibiotic that treats a wide variety of infections; however, it is not usually recommended for children aged less than eight nor in pregnant women in the last half of pregnancy.


  • Take doxycycline as directed. Some branded and generic versions of doxycycline need to be taken one hour prior to or two hours after meals. Ensure you know when to take your branded or generic version of doxycycline. Although tetracyclines, in general, are best taken on an empty stomach, the absorption of doxycycline is not markedly influenced by food or milk.
  • Ensure you maintain hydration while taking doxycycline. This may help reduce the incidence of gastrointestinal side effects.
  • Take exactly as directed and for the duration intended. Do not use to treat any other infection unless instructed to by your doctor. Doxycycline will not treat a cold.
  • Only use when prescribed by a doctor to treat infections caused by susceptible bacteria as improper use increases the chance of resistant bacteria developing.
  • Avoid excessive sun exposure or artificial ultraviolet light while receiving doxycycline; seek medical advice if skin redness or skin eruptions develop. Wear sun protective clothing and consider SPF50+ sun protection when outside if exposure to sunlight is unavoidable.
  • Talk to your doctor immediately if you develop watery or bloody stools, which may be associated with stomach cramps or fever, within a few months of discontinuing doxycycline.

Response and Effectiveness

  • Doxycycline is almost completely absorbed after oral administration. Peak concentrations are reached within two to three hours after dosing; however, it may take up to 48 hours before infection-related symptoms start to abate.
  • Doxycycline is concentrated by the liver in bile and excreted in an active form via the urine and feces.


Doxycycline [Package Insert]. Revised 06/2017. Par Pharmaceutical, Inc

  • Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use doxycycline only for the indication prescribed.
  • Disclaimer: Every effort has been made to ensure that this information is accurate, up-to-date, and complete, but no guarantee is made to that effect. Drug information contained herein may be time sensitive. This drug information does not endorse drugs, diagnose patients or recommend therapy. It is an informational resource designed as a supplement to, and not a substitute for, the expertise, skill, knowledge and judgment of healthcare practitioners. The absence of a warning for a given drug or drug combination in no way should be construed to indicate that the drug or drug combination is safe, effective or appropriate for any given patient. does not assume any responsibility for any aspect of healthcare administered with the aid of this information. The information contained herein is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. If you have questions about the drugs you are taking, check with your doctor, nurse or pharmacist.

Copyright 1996-2018 Revision Date: 2017-07-30 22:44:52