Fosfomycin

What it is

Fosfomycin is an antibiotic that blocks an early enzyme in bacterial cell-wall building, so the wall cannot be assembled and the bacterium dies. Given by mouth as a single sachet dissolved in water, it reaches high concentrations in the urine and stays there for a day or more. It is used for uncomplicated bacterial infections of the bladder.

Used for

• Bacterial infection

What to know while taking it

The sachet is dissolved in water and taken on an empty stomach, since food slows absorption and lowers the amount reaching the urine. It is usually taken at bedtime after emptying the bladder, so the drug sits in the bladder overnight. One dose is the entire course, and no further doses follow even though symptoms may take a couple of days to settle. Loose stools, nausea or headache can occur and are usually short-lived.

When to see a doctor

See a doctor if burning, urgency or lower abdominal pain has not clearly improved within a few days of the dose, or if fever, back or flank pain, or blood in the urine appears, as these suggest the infection has moved beyond the bladder.

Worth knowing

• A single dose is the whole course