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In the U.S.—

Periostat

• Enzyme inhibitor, dental

Doxycycline ( dox-i-SYE-kleen) belongs to the group of medicines known as tetracyclines. Although tetracyclines are antibiotics that are usually used to treat some types of infections, this form of doxycycline is used to help treat periodontitis (a disease of the gums).

The exact way doxycycline works on the gums is not known, but may involve blocking the effect of an enzyme called collagenase.

This medicine is available only with your doctor's prescription, in the following dosage form:

Oral
• Tablets (U.S.)

In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For doxycycline, the following should be considered:

Allergies—Tell your doctor if you have ever had any unusual or allergic reaction to doxycycline or to other tetracyclines. Also tell your health care professional if you are allergic to any other substances, such as foods, preservatives, or dyes.

Pregnancy—Use of doxycycline is not recommended during the last half of pregnancy. Tetracyclines, such as doxycycline, may cause the unborn infant's teeth to become discolored and may slow down the growth of the infant's teeth and bones if they are taken during that time.

Breast-feeding—Use of doxycycline is not recommended since tetracyclines, such as doxycycline, pass into human breast milk. Tetracyclines may cause the nursing baby's teeth to become discolored and may slow down the growth of the baby's teeth. It may be necessary for you to stop breast-feeding during treatment with doxycyline. Be sure you have discussed the risks and benefits of the medicine with your dentist and doctor.

Children—Tetracyclines may cause permanent discoloration of teeth and slow down the growth of bones. Doxycycline should not be given to children up to 8 years of age unless directed by the child's doctor.

Older adults—Many medicines have not been studied specifically in older people. Therefore, it may not be known whether they work exactly the same way they do in younger adults or if they cause different side effects or problems in older people. There is no specific information comparing use of doxycycline in the elderly with use in other age groups.

Other medicines—Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking doxycycline, it is especially important that your health care professional know if you are taking any of the following:

• Anticoagulants (blood thinners)—Tetracyclines may decrease clotting of blood, which could increase the effects of the blood thinner

• Antacids or
• Bismuth subsalicylate (e.g., Pepto-Bismol) or
• Iron-containing medicine—Use of these medicines with doxycycline may decrease the amount of doxycycline absorbed into the body and decrease its effects

• Oral contraceptives (birth control pills)—Use of birth control pills with tetracyclines may decrease the effect of the birth control pills and increase the chance of unwanted pregnancy

• Penicillins—Tetracyclines may decrease the effects of penicillins against infection

It is best if this medicine is taken 1 hour before the morning and evening meals.

Take this medicine with a full glass (8 ounces) of water while you are standing up, to prevent irritation of the esophagus (tube between the throat and stomach) or stomach.

Dosing—

The dose of doxycycline will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of doxycycline. If your dose is different, do not change it unless your doctor tells you to do so.

• For oral dosage form (tablets):
  • For periodontitis (gum disease):
    • Adults—20 mg twice a day.
    • Children—Use in children up to 8 years of age is not recommended. Tetracyclines, such as doxycycline, can permanently discolor teeth.
    • Children 8 years of age and older—Use and dose must be determined by your dentist or doctor.

Missed dose—

If you miss a dose of this medicine, take it as soon as possible. However, if it is almost time for the next dose, skip the missed dose and go back to your regular dosing schedule. Do not double doses.

Storage—

To store this medicine:

• Keep out of the reach of children.
• Store away from heat and direct light.
• Do not store in the bathroom, near the kitchen sink, or in other damp places. Heat or moisture may cause the medicine to break down.
• Do not keep outdated medicine or medicine no longer needed. Be sure that any discarded medicine is out of the reach of children.

Do not take antacids or bismuth subsalicylate within 1 to 2 hours of taking doxycycline. In addition, do not take iron-containing medicines (including vitamin preparations containing iron) within 2 to 3 hours of taking doxycycline. To do so may keep doxycycline from working properly.

Oral contraceptives (birth control pills) may not work properly if you take them while you are taking tetracyclines. Unplanned pregnancies may occur. You should use a different or additional means of birth control while you are taking doxycycline. If you have any questions about this, check with your doctor.

Before having surgery (including dental surgery) with a general anesthetic, tell the medical doctor or dentist in charge that you are taking doxycycline.

Some people who take tetracyclines may become more sensitive to sunlight than they are normally. Exposure to sunlight, even for brief periods of time, may cause severe sunburn; skin rash, redness, itching, or discoloration; or vision changes. When you begin taking this medicine:

• Stay out of direct sunlight, especially between the hours of 10:00 a.m. and 3:00 p.m., if possible.
• Wear protective clothing, including a hat and sunglasses.
• Apply a sun block product that has a skin protection factor (SPF) of at least 15. Some patients may require a product with a higher SPF number, especially if they have a fair complexion. If you have any questions about this, check with your health care professional.
• Do not use a sunlamp or tanning bed or booth.

If you have a severe reaction from the sun, check with your doctor.

Side Effects of This Medicine

Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your dentist or doctor as soon as possible if any of the following side effects occur:

• Rare
  • Increased sensitivity of skin to sunlight;  itching of the rectal or genital areas;  sore mouth or tongue 
  
  

Other side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. However, check with your doctor if any of the following side effects continue or are bothersome:

• Less common
  • Diarrhea;  heartburn;  joint pain;  nausea 
  
  

Other side effects not listed above may also occur in some patients. If you notice any other effects, check with your doctor.

Developed: 01/14/1999

Revised: 07/31/2001