Taking an anticoagulant like warfarin with aspirin which thins the blood could have a more serious effect such as uncontrolled bleeding.
An even more hazardous combination would be to give patients with heart failure a combination of medications which improve blood flow with those that inhibit clotting.
The factors contributing to the severity of a reaction include drug dosage and frequency, the type of interaction, liver and kidney function and age. Older adults metabolize drugs less effectively than younger people.
Interaction with supplements and herbal products
Another type of interaction could occur between supplements and conventional drugs. Many people think of dietary supplements and herbal products as being safe because they are natural, but they can cause harmful side effects when combined with prescription medications. One of these is the popular herbal supplement, St John’s Wort (Hypericum perforatum) which can cause tremors, fever, confusion, and anxiety when taken with antidepressants.
