Some foods alter the absorption of some medicines. In fact, they may slow down, speed up or increase the action of the active substances and as a result cause undesirable effects.
Drug-drug interactions or alcohol-drug interactions are well known to professionals and are always pointed out on the containers of the medications. However, some common foods can also strongly influence the metabolism of oral medicines, increasing their side effects or inhibiting their action. When prescribing a medicine, ask your doctor or pharmacist for details and they will advise you on how to adapt your treatment.
Substances contained in grapefruit inhibit an enzyme that metabolises certain medicines, which increases the absorption of medicines in the intestine. In other cases, grapefruit blocks the absorption of the drug, reducing its effectiveness.
- Statins (Cholesterol): simvastatin, atorvastatin, lovastatin
- Nifedipine (high blood pressure)
- Amiodarone (heart rhythm disturbances)
- Fexofenadine (antihistamine)
- cyclosporine (immunosuppressant)
Bitter oranges can have the same effect, but sweet oranges such as Navel or Valencia do not.
Interactions between dairy products and medicines
Calcium-rich foods reduce the gastrointestinal absorption of antibiotics such as ciprofloxacin or norfloxacin, as well as osteoporosis drugs (bisphosphonates). For this reason, dairy products should be consumed at least one to two hours after taking the medicine. There is also a risk of hypercalcaemia with certain diuretics (hydrochlorothiazide), which reduce urinary excretion of calcium.
Interaction between caffeinated drinks and medicinal products
Antibiotics such as ciprofloxacin and norfloxacin, which are used in particular to treat urinary tract infections (cystitis), reduce the elimination of caffeine and may therefore cause overdosage and increased side effects (panic attacks, excitation, tremors, palpitations, etc.). Theophylline, an antiasthmatic, has the same undesirable effects as caffeine and is therefore added to it. It is therefore advisable to avoid coffee, tea, soft drinks or energy drinks containing caffeine during treatment.
Drug Interactions with liquorice
If consumed in excessive amounts, liquorice may cause cardiac arrhythmias, muscle fatigue and hypertension. In addition, glycyrrhizic acid from the plant affects liver enzymes that metabolise drugs, resulting in slower or increased absorption.
- Digitalis/Digoxin (heart failure)
- Oral contraceptives
- Foods rich in vitamin K
Vitamin K is involved in the synthesis and activation of certain plasma clotting proteins. As a result, it reduces the effectiveness of anticoagulants such as warfarin, which increases the risk of thrombosis. You should not consume more than one portion per day of foods that contain vitamin K in high amounts (cabbage, broccoli, spinach, avocado, parsley, lettuce, beetroot, etc.) and, above all, avoid sudden changes in dietary habits.
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