Doxycycline is a broad-spectrum tetracycline antibiotic used against a wide variety of bacterial infections, including Rocky Mountain spotted fever and other fevers caused by ticks, fleas, and lice; urinary tract infections; trachoma (chronic infections of the eye); and some gonococcal infections in adults. It is an approved treatment for inhalational anthrax. It is also used with other medications to treat severe acne and amoebic dysentery (diarrhea caused by severe parasitic infection of the intestines).

Doxycycline may also be taken for the prevention of malaria on foreign trips of less than 4 months' duration.

Occasionally doctors prescribe doxycycline to treat early Lyme disease and to prevent "traveler's diarrhea." These are not yet officially approved uses for this drug.

Most important fact about this drug

Generally, children under 8 years old and women in the last half of pregnancy should not take this medication. It may cause developing teeth to become permanently discolored. (However, children under 8 may be given this drug for inhalational anthrax.)

How should you take this medication?

Take doxycycline with a full glass of water or other liquid to avoid irritating your throat or stomach. Doxycycline can be taken with or without food. However, if the medicine does upset your stomach, you may wish to take it with a glass of milk or after you have eaten. Doxycycline tablets should be swallowed whole.

Take this medication exactly as prescribed by your doctor, even if your symptoms have disappeared.

If you are taking an oral suspension form of doxycycline, shake the bottle well before using. Do not use outdated doxycycline.

Recommended dosage

ADULTS

The usual dose of oral doxycycline is 200 milligrams on the first day of treatment (100 milligrams every 12 hours) followed by a maintenance dose of 100 milligrams per day. The maintenance dose may be taken as a single dose or as 50 milligrams every 12 hours.

Your doctor may prescribe 100 milligrams every 12 hours for severe infections such as chronic urinary tract infection.

For Uncomplicated Gonorrhea (Except Anorectal Infections in Men)

The usual dose is 100 milligrams by mouth, twice a day for 7 days. An alternate, single-day treatment is 300 milligrams, followed in 1 hour by a second 300-milligram dose.

For Primary and Secondary Syphilis

The usual dose is 200 milligrams a day, divided into smaller, equal doses for 14 days.

For Inhalational Anthrax

To prevent or combat infection after exposure, the usual dose is 100 milligrams taken by mouth twice a day for 60 days. Treatment can be started intravenously, but should be switched to oral doses as soon as possible.

For Prevention of Malaria

The usual dose is 100 milligrams a day. Treatment should begin 1 to 2 days before travel to the area where malaria is found, then continue daily during travel in the area and 4 weeks after leaving.

CHILDREN

For children above 8 years of age, the recommended dosage schedule for those weighing 100 pounds or less is 2 milligrams per pound of body weight, divided into 2 doses, on the first day of treatment, followed by 1 milligram per pound of body weight given as a single daily dose or divided into 2 doses on subsequent days.

For more severe infections, up to 2 milligrams per pound of body weight may be used.

For inhalational anthrax in children weighing less than 100 pounds, the usual dose is 1 milligram per pound of body weight twice daily for 60 days.

For prevention of malaria, the recommended dose is 2 milligrams per 2.2 pounds of body weight up to 100 milligrams.

For children over 100 pounds, the usual adult dose should be used.

If you miss a dose

Take the forgotten dose as soon as you remember. If it is almost time for the next dose, put it off for several hours after taking the missed dose. Specifically, if you are taking one dose a day, take the next one 10 to 12 hours after the missed dose. If you are taking two doses a day, take the next one 5 to 6 hours after the missed dose. If you are taking three doses a day, take the next one 2 to 4 hours after the missed dose. Then return to your regular schedule.

Storage Instructions

Doxycycline can be stored at room temperature. Protect from light and excessive heat.

What side effects may occur?

Side effects cannot be anticipated. If any develop or change in intensity, inform your doctor as soon as possible. Only your doctor can determine if it is safe for you to continue taking doxycycline.

• angioedema (chest pain; swelling of face, around lips, tongue and throat, arms and legs; difficulty swallowing)
• bulging foreheads in infants
• diarrhea
• difficulty swallowing
• discolored teeth in infants and children (more common during long-term use of tetracycline)
• inflammation of the tongue
• loss of appetite
• nausea
• rash
• rectal or genital itching
• severe allergic reaction (hives, itching, and swelling)
• skin sensitivity to light
• vomiting
• aggravation of lupus erythematosus (disease of the connective tissue)
• skin inflammation and peeling
• throat inflammation
• ulcerations

Why should this drug not be prescribed?

If you are sensitive to or have ever had an allergic reaction to doxycycline or drugs of this type, you should not take this medication. Make sure your doctor is aware of any drug reactions that you have experienced.

Special warnings about this medication

As with other antibiotics, treatment with doxycycline may result in a growth of bacteria that do not respond to this medication and can cause a secondary infection.

Bulging foreheads in infants and headaches in adults have occurred. These symptoms disappeared when doxycycline was discontinued.

You may become more sensitive to sunlight while taking doxycycline. Be careful if you are going out in the sun or using a sunlamp. If you develop a skin rash, notify your doctor immediately.

Birth control pills that contain estrogen may not be as effective while you are taking tetracycline drugs. Ask your doctor or pharmacist if you should use another form of birth control while taking doxycycline.

Doxycycline syrup (Vibramycin) contains a sulfite that may cause allergic reactions in certain people. This reaction happens more frequently to people with asthma.

Possible food and drug interactions when taking this medication

If doxycycline is taken with certain other drugs, the effects of either could be increased, decreased, or altered. It is especially important to check with your doctor before combining doxycycline with the following:

• Antacids containing aluminum, calcium, or magnesium, and iron-containing preparations such as Maalox, Mylanta, and others
• Barbiturates such as phenobarbital
• Bismuth subsalicylate (Pepto-Bismol)
• Blood-thinning medications such as Coumadin
• Carbamazepine (Tegretol)
• Oral contraceptives
• Penicillin (V-Cillin K, Pen-vee K, others)
• Phenytoin (Dilantin)
• Sodium bicarbonate

Special information if you are pregnant or breastfeeding

Doxycycline should not be used during pregnancy. Tetracycline can damage developing teeth during the last half of pregnancy. If you are pregnant or plan to become pregnant, inform your doctor immediately. Tetracyclines such as doxycycline appear in breast milk and can affect a nursing infant. If this medication is essential to your health, your doctor may advise you to discontinue breastfeeding until your treatment is finished.

Overdosage

Any medication taken in excess can have serious consequences. If you suspect an overdose, seek medical treatment immediately.

What else is Doxycycline called?

Doxycycline has been trademarked (given brand names) by several companies. These names are as follows: Doxycycline hyclate, Doryx, Doxy-Caps, Doxy-Tabs, Vibramycin, and Vibra-Tabs. By law, the brand name versions of a generic drug all need to have the same ingredients as the generic version. The only difference between medications with brand names and those without brand names is the price.