Doxycycline is a broad-spectrum antibiotic used to treat a variety of bacterial infections. This medication is in a class of drugs called tetracyclines, and it works by stopping the growth of bacteria.

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Reviewed by Olivia Irving, PhD, On November 2, 2023

It should only be used as prescribed and under medical supervision.

Home » Antibiotics » Doxycycline

What is Doxycycline?

This medicine is an antibiotic that belongs to the semi-synthetic group of tetracyclines. It can be utilized both orally and parenteral. It was introduced by Pfizer in 1967 and since then has become one of the most effective and popular options for the cure of infections.

The mechanism of action and when is it applicable?

Doxycycline works by blocking the process of protein synthesis in the bacterial cells. The active molecule distinguishes them and prevents their growth and development.
Thus, this antibiotic is good for combating of infections caused by various microorganisms, namely:

  • respiratory tract issues, such as pneumonia, chronic bronchitis, sinusitis;
  • urinary tract issues;
  • sexually transmitted infections like chlamydia, gonorrhea and syphilis;
  • skin problems, such as acne, when antibiotic therapy is needed.

How to use Doxycycline?

The medicine is available in tablets and capsules of 0.05, 0.1 and 0.2 g. There is also a syrup of 20 and 60 ml, ampoules with powder for injections of 0.1 and 0.2 g and vials for injections of 5 ml (100 mg).

The oral forms are used during or after meals to reduce the risk of stomach irritation. It is necessary to drink a sufficient amount of liquid with a pill. It can also be milk, as it does not prevent the adsorption of an active ingredient. Simultaneous consumption of food also does not affect this process.

The doctor determines the duration of the course individually. Usually, it lasts for at least 24-48 hours after the symptoms of the disease disappear and body temperature normalizes. In some cases, it can take longer to prevent certain complications.

For adults and children older than 12 years and with a body weight of more than 45 kg, the daily dose is 200 mg during the first days and 100 mg on the following days. If the infection is severe or chronic, the drug should be utilized at a dose of 200 mg per day throughout the treatment.

Possible adverse effects of Doxycycline

Severe side effects are not common for this medicine. However, its utilization may be accompanied by:

  • allergic reactions, mainly skin rash;
  • digestive system issues like nausea, vomiting, abdominal pain;
  • nervous system issues, such as headache, dizziness, blurred vision or loss of vision;
  • cardiovascular system issues like arterial hypotension and tachycardia;
  • musculoskeletal system may sometimes react with pain;
  • sometimes changes in laboratory tests are observed;
  • phlebitis rarely occurs as a result of intravenous administration.

In children, there may occur a violation of the formation of bone tissue, slowing down of bone growth, defects in tooth enamel and a change in the color of teeth. Scientific investigations show that this happens mainly in small children who are younger than 5 years. That is why this medicine is usually not prescribed for them.

The most common contraindications

Doxycycline is contraindicated for the following patients:

  • hypersensitivity to tetracyclines or any type of allergic reaction;
  • severe liver failure;
  • leukopenia;
  • pregnancy and breastfeeding;
  • children under 5 years of age.

Prescriptions for children from 8 to 12 years old should be carried out with caution. According to studies, Doxycycline is safe for use in children older than 5 years but still a specialist should monitor the treatment.


Altogether, Doxycycline is a powerful antibiotic that is prescribed for both children and adults to treat various infections. Usually, it requires a prescription and a visit to the doctor. In addition, a specialist selects the dose and duration of the course.

Modern pharmaceutical online services allow purchasing Doxycycline online after the consultation. Thus, one can also benefit from this possibility and get the needed treatment.


What are the available dosage forms of Doxycycline?

There are tablets and capsules of 0.05, 0.1 and 0.2 g, a syrup of 20 and 60 ml, ampoules with powder for injections of 0.1 and 0.2 g and vials for injections of 5 ml (100 mg).

Is Doxycycline safe for children?

This medicine can be prescribed for children older than 5 years and with caution for children from 8 to 12 years old.

Who cannot use Doxycycline?

This medicine is contraindicated for patients with hypersensitivity to tetracyclines, severe liver failure and leukopenia. Also, it is not prescribed during pregnancy and breastfeeding and for children under 5 years of age.

What is Doxycycline used for?

Doxycycline is used to treat many different bacterial infections, such as urinary tract infections, acne, gonorrhea, chlamydia, periodontitis (gum disease), and others. It’s also used to treat blemishes, bumps, and acne-like lesions caused by rosacea. However, it won’t treat facial redness caused by rosacea.

How should Doxycycline be taken?

Doxycycline is usually taken once or twice a day, with a full glass of water and while standing or sitting up to prevent irritation of the throat. It’s important to follow the instructions provided by your healthcare provider, as the dosage and length of treatment can vary depending on the condition being treated.

Can Doxycycline be taken with food?

Yes, Doxycycline can be taken with or without food. However, it should not be taken with dairy products or calcium-fortified juices alone, as calcium can affect the absorption of the medication.

Are there any side effects of taking Doxycycline?

Common side effects of Doxycycline may include nausea, diarrhea, upset stomach, skin rash or itching, or vaginal itching or discharge. More severe side effects, which require immediate medical attention, may include body aches, fever, chills, severe blistering, peeling, and a red skin rash.

Can you drink alcohol while taking Doxycycline?

It’s generally advised to avoid alcohol while taking Doxycycline, as alcohol can decrease its efficacy and increase the risk of side effects.

Is Doxycycline safe during pregnancy or while breastfeeding?

Doxycycline is not recommended for use during pregnancy as it can harm the unborn baby or cause permanent tooth discoloration later in life. It can also pass into breast milk and may affect bone and tooth development in a nursing infant. Always consult your healthcare provider for advice.

Can Doxycycline cause allergic reactions?

Yes, Doxycycline can cause allergic reactions in some people. Symptoms may include hives, difficulty breathing, and swelling of the face, lips, tongue, or throat. Seek emergency medical attention if you experience any of these symptoms.

How long does it take for Doxycycline to work?

The length of time it takes for Doxycycline to work can vary depending on the type of infection. Some people might start to feel better within a few days, but it is important to take the full course of antibiotics as prescribed to fully eradicate the infection.

Can Doxycycline be used to treat viral infections like the common cold or flu?

No, Doxycycline is an antibiotic and is only effective against bacterial infections. It will not work for viral infections (such as the common cold, flu).

What should I do if I miss a dose of Doxycycline?

If you miss a dose of Doxycycline, take it as soon as you remember. However, if it’s almost time for your next dose, skip the missed dose and return to your regular schedule. Do not take extra medicine to make up the missed dose.