Wednesday, February 1, 2012


Taking Antibiotics

For severe bacterial infections, antibiotics are usually first given by injection (usually into a vein but sometimes into a muscle). When the infection is controlled, antibiotics can then be taken by mouth. For less severe infections, antibiotics can be given by mouth from the start.

Antibiotics need to be taken until the infecting bacteria are eliminated from the body, which may be days after the symptoms disappear. So people must take them for the entire time prescribed whether they have symptoms or not. Antibiotics are rarely given for fewer than 5 days. (An exception is certain uncomplicated urinary tract infections.) Stopping treatment too soon can result in a return of the infection or the development of antibiotic-resistant bacteria.

A doctor, nurse, or pharmacist can explain how the prescribed antibiotic should be taken and what side effects it may have. Some antibiotics must be taken on an empty stomach. Others may be taken with food. Metronidazole, a common antibiotic, causes an unpleasant reaction with alcohol. Also, some antibiotics can interact with other drugs people may be taking, possibly reducing the effectiveness or increasing the side effects of the antibiotic or the other drugs. Some antibiotics make the skin sensitive to sunlight.

Antibiotics are sometimes used to prevent infections (called prophylaxis). Antibiotics may be given to people who have been exposed to a person with meningitis to prevent meningitis from developing. Some people with abnormal or artificial heart valves take antibiotics before dental and surgical procedures to prevent bacteria from infecting the damaged or artificial valves (such procedures can allow bacteria to enter the body). People undergoing surgery with a high risk of introducing infection (such as major orthopedic or intestinal surgery) may be given antibiotics immediately before the operation. To be effective and to avoid the development of resistance in bacteria, preventive antibiotics are used for only a short time. Antibiotics may also be given to people who have a weakened immune system, such as people with leukemia, people taking chemotherapy for cancer, or people with AIDS, because such people are particularly susceptible to serious infections. They may need to take the antibiotics for a long time.