Doxycycline vs. minocycline

• Doxycycline and minocycline are tetracycline antibiotics used to treat many different types of infections, including respiratory tract infections due to Hemophilus influenzae, Streptococcus pneumoniae, or Mycoplasma pneumoniae. Doxycycline and minocycline are also used to treat Rocky Mountain spotted fever, typhus, and acne.
• Brand names for doxycycline include Vibramycin, Oracea, Adoxa, Atridox, Acticlate, Acticlate Cap, Doryx, Doxteric, Doxy, and Monodox.
• Brand names for minocycline include Dynacin, Minocin, and Solodyn.
• Side effects of doxycycline and minocycline that are similar include diarrhea or loose stools, nausea, vomiting, tooth discoloration, and photosensitivity (exaggerated sunburn).
• Side effects of doxycycline that are different from minocycline include abdominal pain.
• Side effects of minocycline that are different from doxycycline include headache, fatigue, dizziness, itching, and reduced bone development in children.

Doxycycline is a tetracycline antibiotic used to treat many different types of infections, including respiratory tract infections due to Hemophilus influenzae, Streptococcus pneumoniae, or Mycoplasma pneumoniae. Doxycycline is also used to treat Rocky Mountain spotted fever, acne, typhus, nongonococcal urethritis, chancroid, cholera, brucellosis, anthrax, syphilis, and periodontal disease.

Minocycline is a tetracycline antibiotic used to treat bacterial infections caused by Mycoplasma pneumoniae, Chlamydia trachomatis, Borrelia recurrentis, Yersinia pestis, Escherichia coli, Enterobacter aerogenes, Shigella species, Acinetobacter species, respiratory tract infections caused by Haemophilus influenzae and Streptococcus pneumoniae, and respiratory tract and urinary tract infections caused by Klebsiella species. Minocycline is also used to treat inflammatory lesions of non-nodular moderate-to-severe acne, Rocky Mountain spotted fever, typhus, Q fever, and rickettsialpox and tick fevers caused by Rickettsiae.

Doxycycline

Doxycycline is generally well tolerated. The most common side effects are:

• Diarrhea or loose stools
• Nausea
• Abdominal pain
• Vomiting

Tetracyclines, such as doxycycline, may cause tooth discoloration if used in persons below 8 years of age. Exaggerated sunburn can occur with tetracyclines; therefore, minimize sunlight exposure during treatment.

Minocycline

Side effects of minocycline are:

• Nausea
• Vomiting
• Diarrhea
• Headache
• Fatigue
• Dizziness
• Itching
• Photosensitivity
• Tooth discoloration
• Reduced bone development in children

Doxycycline

• The absorption of doxycycline is not markedly affected by food, and therefore, it can be taken with meals.
• For most infections, doxycycline is taken once or twice daily for 7 to 14 days.
• For adult infections, the usual dose of oral doxycycline is 200 mg on the first day of treatment (100 mg every 12 hours) followed by a dose of 100 to 200 mg/day as a single dose or divided and administered twice daily.

Minocycline

• Adults (immediate-release tablets and capsules): The recommended dose for minocycline is 200 mg initially, followed by 100 mg every 12 hours. If more frequent doses are preferred, then two or four 50 mg capsules initially, followed by 500 mg four times a day.
• Children 8 years of age and older (immediate-release tablets and capsules): The recommended dose of minocycline is 4 mg/kg initially, followed by 2 mg/kg every 12 hours, not to exceed the usual adult dose.
• Adults and children 12 years of age and older (extended-release tablets): The recommended dose for minocycline is approximately 1 mg/kg by mouth once daily for up to 12 weeks for the treatment of inflammatory lesions of non-nodular acne.

Doxycycline

• Do not take doxycycline at the same time as aluminum-, magnesium-, or calcium-based antacids such as Mylanta, Maalox, Tums, or Rolaids because, like food, these medications bind doxycycline in the intestine and prevent its absorption. Similarly, do not take doxycycline with minerals (such as calcium or iron) or with bismuth subsalicylate (Pepto Bismol).
• Doxycycline may enhance the activity of warfarin (Jantoven, Coumadin) and cause excessive "thinning" of the blood leading to exaggerated bleeding, necessitating a reduction in the dose of warfarin. Phenytoin (Dilantin), carbamazepine (Tegretol), and barbiturates (such as phenobarbital) may enhance the metabolism (destruction) of doxycycline, thus making it less effective.
• Doxycycline may interfere with the action of penicillins and should not be combined with penicillins. It may also reduce the effect of oral contraceptives. Combining tetracycline and methoxyflurane (Penthrane) may reduce kidney function.

Minocycline

• Minocycline should be used with caution with anticoagulant medications such as warfarin (Coumadin) because it increases the risk of bleeding and bruising.
• Antacids containing aluminum, calcium, magnesium, and iron can bind with minocycline, delay the absorption, and reduce the effectiveness of minocycline.
• Minocycline should be used with caution with oral contraceptives because it may decrease the effectiveness of oral contraceptives.

Doxycycline

• Tetracycline antibiotics, such as doxycycline, can have toxic effects on development of bone in the fetus. Therefore, tetracyclines are not recommended during pregnancy unless there is no other appropriate antibiotic.
• Doxycycline is secreted into breast milk but the extent of absorption by the breastfed infant is not known. Since tetracyclines can cause toxic effects on bone, the use of tetracyclines in nursing mothers is of concern. The physician must decide whether to recommend that a nursing mother discontinue nursing during treatment with tetracyclines or change to a different antibiotic.

Minocycline

• Minocycline should be avoided in pregnant women because it crosses the placenta and may cause fetal harm.
• Minocycline is excreted in human milk, and there is potential for serious adverse effects involving the development of teeth and bones in nursing infants. A decision should be made to discontinue medication or stop nursing, taking into account the importance of the drug to the mother.