Sometimes, medications seem to lose their effectiveness after a few days of use, leading people to assume the drugs are fake, expired, or wrongly prescribed. Others even blame external forces for their ongoing illness. However, a little-known but critical factor is that some common foods can interfere with medications—either reducing their effectiveness or causing harmful side effects. Here are six dangerous food and drug combinations to be aware of:

1. Bananas and Anti-Hypertensive Drugs
Bananas are known for their high potassium content, which is usually healthy. However, anti-hypertensive medications also raise potassium levels in the blood. Combining the two can cause excessive potassium, which may result in irregular heartbeat, palpitations, or arrhythmias. If you’re on blood pressure medication, it’s best to monitor your banana intake to avoid stressing your heart.

2. Vitamin C and Anti-Malaria Drugs
While Vitamin C is generally beneficial, taking it with anti-malaria drugs can backfire. Vitamin C boosts iron absorption, and excess iron helps malaria parasites multiply in the liver, where they reside. This can weaken the effect of the medication. So, if you’re treating malaria, it’s wise to hold off on citrus fruits or Vitamin C supplements.

3. Painkillers and Soft Drinks
Soft drinks contain carbonated water, which increases drug absorption in the body when taken with painkillers. The carbon dioxide and acid present can intensify the concentration of painkillers in your bloodstream, increasing the risk of toxicity or overdose. Always take medications with plain water unless advised otherwise by a doctor.

4. Dairy Products and Antibiotics
Dairy products such as milk and cheese contain calcium, which binds with antibiotics like tetracycline and penicillin. This prevents the drugs from being absorbed effectively into the bloodstream, reducing their ability to fight off infections. To ensure full effectiveness, avoid dairy close to your antibiotic dose.