Tetracycline is an antibiotic that may be prescribed to treat some types of rosacea, which is a condition that causes redness, irritation and swelling of the face. It is generally effective at reducing inflammation after one to two months, but does not generally reduce redness and is not curative. Doxycycline is the tetracycline derivative most often prescribed for rosacea.
There are four subtypes of rosacea, which may become progressively worse if left untreated. Subtype 1 causes redness that may resemble sunburn, but no inflammation. Subtype 2 causes swelling and acne-like pustules on the face. Subtypes 3 and 4 cause severe swelling of the nose and eventually eye irritation. Using tetracycline for rosacea is often effective at reducing the swelling and acne-like pustules of subtype 2, but it does not treat the symptoms of the other subtypes.
Taking tetracycline for rosacea works primarily by directly reducing inflammation rather than by killing bacteria. Unlike acne pustules, which can also be treated with tetracycline, the pustules caused by rosacea generally do not contain bacteria. Tetracycline, however, reduces swelling by keeping small blood vessels in the face intact and by reducing skin sensitivity.
A course of tetracycline for rosacea typically begins with a dosage of around 100 milligrams twice a day. If that treatment produces marked improvement after one or two months, the dosage may be lowered to a single daily extended-release tablet of 40 milligrams. This dosage is known as an anti-inflammatory dose or sub-antimicrobial dose, because it is not sufficient to kill bacteria, but it is usually effective at keeping inflammation at bay. Alternatively, once inflammation is under control, the doctor may prescribe a topical antibiotic that is applied directly to the skin.
The anti-inflammatory dose or topical antibiotic is preferred when possible because patients on a lower dose of tetracycline for rosacea are less likely to experience side effects, such as diarrhea or sensitivity to light, than those on a higher dosage. Additionally, the prevalence of tetracycline and tetracycline derivatives for treating bacterial infections has led to some bacteria strains becoming resistant to these drugs. Reducing the number of patients on these medications within a population helps the drugs stay effective longer.