BERLIN - Just a slosh of milk to whiten your coffee is enough to limit or even block the effect of some antibiotics and osteoporosis medications, German pharmacists are warning.
Food-drug combinations can have unwanted consequences, but many people don't think of coffee as a culprit.
The Federal Union of German Associations of Pharmacists (ABDA) explains that the calcium in milk binds with certain drugs in the digestive tract to form less soluble compounds that cannot be absorbed into the bloodstream.
That is why German pharmacies warn customers that after taking antibiotics and osteoporosis drugs, patients should wait two hours before drinking a cup of coffee with milk.
Other interactions abound. Patients who take anticoagulants, also called vitamin K antagonists, should avoid goji berries. Although the mechanism behind the interaction remains unclear, the ABDA said, the berries increase the drugs' effect and can cause bleeding.
Liquorice is another food that sometimes carries risks. Since it contains substances that raise blood pressure, it can reduce the effect of hypertension medications, the ABDA said.
In addition, it stimulates the release of potassium by the kidneys, which can lead to muscle weakness.
The ABDA recommends that people with high blood pressure eat little or no liquorice.
Grapefruit and pomelos should be avoided by patients taking drugs to treat high blood cholesterol levels or to suppress the immune system, for example after an organ transplant.
The ABDA said that chemicals in the fruits unfavourably affected the breakdown and transport of the drugs in the body, which could either intensify or diminish their effect.