NEW YORK (Reuters Health) - Calcium and iron-rich mineral waters limit the effectiveness of certain medications, such as thyroid preparations and osteoporosis drugs, according to the Chamber of Pharmacists in Lower Saxony. These drugs should be taken with tap water.

In addition, foods containing vitamin K such as spinach and cabbage limit the effects of medications for bleeding.

The Chamber also pointed out that grapefruit has a negative effect on the effectiveness of some drugs; it contains substances that are incompatible with some medical drugs.

She explained that this applies to drugs containing the active substance «Sildenafil» and drugs lowering cholesterol containing the active substance «Simvastatin» and blood pressure drugs containing the active substance «Amlodipine» and «Verapamil» and hypnotics containing the active substance «Zolpidem».

Therefore, grapefruit or juice should not be taken if one of these medications is taken.