Antibiotics and how they work in acne

Antibiotics work by killing bacteria that contribute to the cause of acne. They also have a direct effect of reducing inflammation. Antibiotics usually work well to clear inflamed acne spots, and any surrounding skin inflammation. However, they have little effect on unplugging blocked pores (which you can see as blackheads and whiteheads). So, if you only have mild acne with just blackheads and whiteheads, you are better off using a topical treatment that unblocks pores. If you have a lot of blackheads and whiteheads as well as inflamed acne spots, you may be advised to use a topical treatment such as benzoyl peroxide in addition to taking an antibiotic tablet.

Always read the leaflet that is in the packet of antibiotics. Things such as precautions and possible side-effects vary between different antibiotics. The following are some general points.

Tetracycline based antibiotics

These are the most commonly used antibiotics to treat acne. They include: oxytetracycline, tetracycline, doxycycline, lymecycline and minocycline.

• Children under 12 years should not take tetracycline based antibiotics.
• Do not take tetracycline based antibiotics if you are pregnant, breastfeeding, or intend to become pregnant. Discuss contraception with your doctor if necessary.
• Food and milk affects the absorption of oxytetracycline or tetracycline. Therefore, take these tablets on an 'empty stomach', between meals, with a glass of water, (not milk). Doxycycline, lymecycline and minocycline can be taken with food.
• Women taking 'the pill' should use additional contraceptive precautions (such as condoms) during the first three weeks of taking antibiotics.

Other antibiotics

Other antibiotics that are sometimes used include erythromycin and trimethoprim. You may be advised to take one of these if one of the above has not worked well, or is unsuitable.

How long is treatment needed?

Whatever treatment is used, it is normal to take up to four weeks for there to be any noticeable improvement in the skin. There is often a good response to treatment by six weeks. However, it can take up to four months (sometimes longer) for maximum response to a treatment, and for the skin to be generally free of spots. The most common reason for a treatment failure is because some people think that treatment is not working after a couple of weeks or so, and give up.

Therefore, persevere with any treatment for at least six weeks before deciding if it is working or not. If there is no improvement after six weeks of taking a treatment regularly and correctly, do not despair. Adding in another treatment, or a change to a different or more powerful treatment will usually be advised, and is likely to work. Although treatment can usually clear most spots, there is no treatment that will make your skin perfect, and the odd spot may remain.

Will acne return after treatment?

Once the spots have cleared, acne commonly flares up again if you stop treatment. Therefore, after the spots have gone or are much reduced, it is common to carry on with a 'maintenance' treatment to prevent acne from flaring up again. It is common to need maintenance treatment for 4-5 years to keep acne away. This is typically until the late teens or early 20s. In a small number of cases, acne persists into the 30's, or even later. For these people it is possible to continue to treat the skin to keep it under control.

Maintenance treatment is usually with a topical treatment - either benzoyl peroxide or a topical retinoid. These can both be used indefinitely. The dose used to prevent spots from returning is often lower than that used to treat acne. For example, one application to the skin every other day with a low strength preparation may be sufficient to keep spots from returning.

It is not usual to take antibiotic tablets (or use topical antibiotics) for maintenance treatment once the spots have cleared. This is because long-term use of antibiotics can lead to resistance of germs to the antibiotics. Therefore, if at first you are treated with an antibiotic, you may be advised to switch to benzoyl peroxide or a topical retinoid for maintenance treatment.