Doxycycline is an antibiotic that can treat various bacterial infections. People can use oral or injectable forms.

Sometimes, doctors use doxycycline to treat lung, nose, and throat infections. People can also use doxycycline to treat acne and rosacea.

Doxycycline may not be appropriate for everyone. It may interact with some other drugs and can cause side effects. Doctors will use caution when prescribing doxycycline to children and pregnant women.

In this article, we look at the many uses of doxycycline. We also discuss the side effects and warnings for people taking doxycycline.

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A doctor may prescribe doxycycline to treat many bacterial infections, including lung infections and STIs.

Doxycycline is an antibiotic in the tetracycline class. Doctors prescribe doxycycline for various bacterial infections such as:

People can also take doxycycline in the following situations:

Many bacteria have developed a resistance to doxycycline. When doctors want to prescribe doxycycline, they can test the bacteria to make sure it will respond to the treatment.

If the benefits outweigh the risks, doctors can prescribe doxycycline to children 8 years old or younger who have severe or life threatening infections.

The brand name of doxycycline delayed release tablets is Doryx and Doryx MPC.

Vibramycin is another brand name of doxycycline that is available in the following formulations:

  • powder for suspension
  • syrup
  • capsule

Oracea is the brand name of the doxycycline product doctors use to treat rosacea lesions in adults.

Doxycycline is available in seven different formulations. The following table lists the various forms and their strengths in milligrams (mg), or milligrams per 5 milliliters (mg per 5 ml).

Doxycycline productFormStrength
Vibramycincapsule100 mg
syrup50 mg per 5 ml teaspoon
suspension25 mg per 5 ml teaspoon
DoryxDelayed release tablets50 mg and 200 mg
Delayed release capsules75 mg and 100 mg
Doryx MPCDelayed release tablet120 mg
Oraceacapsule40 mg
Acticlatetablet75 mg and 150 mg
Doxycycline for injectionpowder for solution100 mg per vial
Doxycycline genericcapsules50 mg, 75 mg, 100 mg, and 150 mg
tablet20 mg, 50 mg, 75 mg, 100 mg, and 150 mg
Delayed release tablet50 mg, 75 mg, 150 mg, and 200 mg

Doryx MPC is a delayed release tablet with a special coating called a modified polymer enteric coat (MPC). This coating is resistant to acid and delays the release of doxycycline by 15–20 minutes.

Doctors will recommend taking doxycycline with a full glass of water to prevent it from irritating the esophagus, which is the tube that connects the stomach and the mouth.

If someone has irritation in their esophagus, they can take doxycycline with food or milk. People who take doxycycline with food or milk may absorb less doxycycline, but this should not significantly impact the results.

Doxycycline has many uses and, depending on the indication, the doctor will prescribe a different dose.


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A doctor can advise on the correct dosage of doxycycline to give a child.

If a child, weighing less than 45 kilograms (kg), has a severe or life threatening infection, the doctor will prescribe 2.2 milligrams per kilogram (mg/kg) of the child’s body weight every 12 hours. Children weighing more than 45 kg can receive an adult dose.

Children 8 years and older with less severe infections and weighing less than 45 kg will receive 4.4 mg/kg in two doses on the first day. For the following days, the doctor will prescribe 2.2 mg/kg as a single dose or divided into two doses.

If the child weighs more than 45 kg and has a less serious infection, the doctor can prescribe the adult dosage.


When treating less serious infections in adults, doctors will prescribe 100 mg of doxycycline twice a day on the first day, followed by 100 mg once a day. If the infection is severe or life threatening, the doctor will prescribe 100 mg twice a day.

Doxycycline may not be appropriate for everyone. Anyone who has previously had a serious reaction to doxycycline or any other tetracycline should avoid doxycycline.

During tooth development, which occurs in the second half of pregnancy, in infancy, and childhood up to 8 years old, doxycycline may cause permanent tooth discoloration. Teeth may become a yellow-gray-brown color.

Doctors must evaluate the risks and benefits of prescribing doxycycline to young children or women during pregnancy.

Some people may develop Clostridium difficile diarrhea when taking doxycycline. This intestinal infection can range from mild to fatal.

The following table lists the possible side effects of doxycycline by body system.

Body systemSide effect
Stomach and intestines loss of appetite
inflammation and soreness of the tongue
difficulty swallowing
inflammation of the digestive tract
inflammation of the pancreas
inflammatory lesions on the anus and genitals
Skinsun sensitivity
severe rashes
Kidneyskidney toxicity
Immune systemallergic reaction
fluid buildup
anaphylactic shock
pericarditis, or inflammation of the lining of the heart
low count of white blood cells or platelets
disruption in immune cell counts
Otherhigh blood pressure in the skull

Tetracyclines, the drug class that includes doxycycline, may cause bleeding.

People who are taking drugs that prevent blood from clotting, known as anticoagulants, may need to take a smaller dose of their anticoagulant.

Doctors will not prescribe a penicillin antibiotic with doxycycline. Penicillins are antibiotics that kill bacteria, whereas doxycycline stops the growth of bacteria. When given together, doxycycline may block the action of penicillin.

Some over-the-counter antacids can affect how well the body absorbs doxycycline, including those that contain:

Doctors may advise people taking birth control pills to use a second method of contraception while taking doxycycline. This is because the antibiotic can reduce the effectiveness of oral contraceptives.

Other drugs that may interact with doxycycline include:

  • barbiturates
  • carbamazepine
  • phenytoin

Doctors should take a full medication history before prescribing doxycycline.

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Research has shown that doxycycline is unlikely to cause birth defects.

Researchers suggest that therapeutic, short term treatments with doxycycline during pregnancy are unlikely to cause birth abnormalities, according to the currently available data.

During the last half of pregnancy, doctors will prescribe doxycycline carefully, especially if the person needs long term use or repeated short term courses. Some children, as they grow, may develop yellow-gray-brown teeth discoloration if exposed to doxycycline.

Doxycycline can find its way into breast milk, so breastfeeding while taking the drug can expose an infant to the antibiotic. Researchers are unsure how much doxycycline will pass to the infant through breast milk.

Doctors may prescribe short courses of doxycycline to a nursing parent. The benefits to the parent must outweigh the possible risks to the infant. Researchers are unsure of the effect on infants of extended periods of exposure to doxycycline in breast milk.

Doctors prescribe doxycycline to treat serious bacterial infections. People also use doxycycline to control acne and rosacea.

Before taking doxycycline, people should let their doctors know of any other medications they are taking. Doxycycline may not be appropriate for everyone, especially during pregnancy. The doctor must weigh the benefits of treatment with the possible risks.

Children 8 years old and younger can take doxycycline, but they are at risk of permanent discoloration of the teeth. Doctors will decide if the drug is safe or if an alternative treatment is more appropriate.