Doxycycline

💊 What is Doxycycline used for?

• •Rocky Mountain spotted fever, typhus fever, Q fever, rickettsialpox, and tick fevers caused by Rickettsiae
• •Respiratory tract infections caused by Mycoplasma pneumoniae
• •Lymphogranuloma venereum and some chlamydia infections (urethral, cervical, or rectal) caused by Chlamydia trachomatis
• •Psittacosis (ornithosis), trachoma, and inclusion conjunctivitis caused by chlamydia-type bacteria
• •Nongonococcal urethritis caused by Ureaplasma urealyticum
• •Relapsing fever caused by Borrelia recurrentis
• •Chancroid, plague, tularemia, cholera, campylobacter infections, bartonellosis, and granuloma inguinale
• •Brucellosis, where the label says it is used together with streptomycin
• •Some infections caused by certain gram-negative bacteria, but only when lab testing shows the bacteria are susceptible to the drug

How it works

How it is usually taken

• •The label says doxycycline should be used only to treat or prevent infections that are proven or strongly suspected to be caused by bacteria it works against. It should be taken exactly as directed, and people are usually told to keep taking it for the full course, even if they start to feel better early. Drink plenty of fluids with each dose to help reduce irritation of the esophagus (the tube from the mouth to the stomach). If the medicine upsets your stomach, the label says it can be taken with food or milk. Food and milk do not greatly change how well it is absorbed, but calcium-rich foods can reduce absorption. Follow the instructions from your prescriber or pharmacist.

Comes as

• •Tablets in 150 mg, 100 mg, 75 mg, and 50 mg strengths (doxycycline monohydrate)
• •The 100 mg tablet is described as a peach-colored, film-coated, round tablet

⚠️ Doxycycline side effects

🛑 Who should not take Doxycycline, and who should be careful

The label says not to take it if

• 🚨You have shown an allergic reaction (hypersensitivity) to any tetracycline medicine. The label says this drug is contraindicated in that case.

Tell your doctor before taking it if

• •Tell your prescriber about all medicines you take, including blood thinners, antacids, iron products, and oral contraceptives.
• •Tell your prescriber if you are pregnant, may become pregnant, or are breastfeeding.
• •Tell your prescriber if you have had intracranial hypertension, or if you are an overweight woman of childbearing age, since the label says these people are at greater risk.
• •Tell your prescriber if you have a history of allergies to antibiotics.
• •The label advises against use in children 8 years of age or younger unless the benefits are expected to outweigh the risks in severe or life-threatening conditions.

🔀 Doxycycline with other medicines, food and alcohol

The label says to discuss these with your doctor or pharmacist

• •Blood thinners (anticoagulants): doxycycline can lower prothrombin activity, so the label says these patients may need a lower anticoagulant dose.
• •Penicillin: the label advises avoiding giving tetracyclines together with penicillin because they can interfere with its action.
• •Antacids containing aluminum, calcium, or magnesium, iron products, and bismuth subsalicylate: these can reduce how well doxycycline is absorbed.
• •Barbiturates, carbamazepine, and phenytoin: these can shorten how long doxycycline stays in the body.
• •Oral contraceptives: the label says concurrent use with tetracyclines may make them less effective.
• •Isotretinoin: the label says combined use should be avoided because isotretinoin can also cause intracranial hypertension.
• •Calcium-rich foods: these can reduce absorption of tetracyclines.

Alcohol and food

The label does not mention alcohol. The label says absorption of tetracyclines is reduced when taken with foods, especially those containing calcium, but food or milk does not markedly change doxycycline absorption. Drink plenty of fluids with the medicine, and avoid excessive sunlight or artificial UV light while taking it.

🤰 Doxycycline in pregnancy and breastfeeding

Pregnancy

The label says tetracyclines cross the placenta and can have toxic effects on the developing fetus, often related to slowed skeletal development. Animal studies showed embryo toxicity when given early in pregnancy. If a patient becomes pregnant while taking it, or uses it during pregnancy, the label says the patient should be told about the potential hazard to the fetus. The label also says use during tooth development (the last half of pregnancy through age 8) may permanently discolor teeth.

Breastfeeding

The label says tetracyclines, including doxycycline, are excreted in human milk, and it is not known how much the breastfed infant absorbs. It says short-term use by lactating women is not necessarily contraindicated, but the effects of prolonged exposure are unknown. The label says a decision should be made whether to stop nursing or stop the drug, considering how important the drug is to the mother.

🗓️ Storage, missed doses and taking too much

Storage

The label says to store at 20° to 25°C (68° to 77°F), protect from light, and keep in a tight, light-resistant container. It also says not to use outdated or poorly stored doxycycline.

If a dose is missed

The label does not say.

If too much is taken

The label says that if an overdose happens, the medicine should be stopped, symptoms treated, and supportive measures used. It also says dialysis does not change the serum half-life and would not help in an overdose. If you think someone has taken too much, contact a doctor, pharmacist, or emergency services right away.

🗒️ Questions to ask about Doxycycline

• Is this infection likely caused by bacteria that doxycycline can treat?
• How should I take doxycycline with food, milk, or antacids so it works well?
• How long do I need to keep taking it, and what should I do if I feel better early?
• How can I protect my skin from sunlight while I am taking this medicine?
• What should I do if I get watery or bloody diarrhea during or after treatment?
• Could doxycycline affect my other medicines, such as blood thinners or birth control?
• Is doxycycline safe to use if I am pregnant or breastfeeding?

❓ Doxycycline: frequently asked questions