How to Avoid Common Food & Medication Interactions

Prescription medication labels advise how much to take, how often and for how long. But they often don’t explain how certain foods might interact with them.

“Understanding how certain foods can affect the way medications work is essential for safety and to ensure maximum benefit,” says Yongjin Chen, MD, PhD, a family medicine specialist at University Hospitals. “Slower absorption, reduced effectiveness and an increased risk of side effects are just some of the potential risks.” He shares more about common medication and food interactions. 

What to Avoid and Why

You may be advised to avoid certain foods and beverages for a specific timeframe, such as two hours before or after taking the medication. In other cases, some foods and beverages should be avoided entirely. Your doctor or pharmacist can provide guidance about how to take a medication for maximum benefit and minimum risk. 

Antibiotics. You may be advised to avoid or limit dairy products and antacids with calcium when taking certain antibiotics. Calcium can bind to antibiotics in the stomach, reducing absorption and effectiveness. In addition, pineapple and pineapple juice should be avoided. It contains bromelain, an enzyme that can interact with certain antibiotics and cause rash, nausea, diarrhea and mouth tenderness/irritation.

Antidepressants. Some antidepressant medications like monoamine oxidase (MAO) inhibitors decrease the production of enzymes that regulate neurotransmitters in the brain, like serotonin and dopamine. With less MAO, the breakdown of these “feel-good” chemicals is slowed and their levels rise, which may improve mood and other depression symptoms.

You should avoid aged cheeses, cured meats, fermented vegetables, beer, red wine and soy products when taking MAO inhibitors. These foods contain high levels of tyramine, an amino acid that also requires MAO for breakdown. Too much tyramine in the blood can cause a sudden increase in blood pressure that can be life-threatening.

Blood Pressure Medications. Common blood pressure medications like ACE inhibitors and angiotensin receptor blockers (ARBs) increase potassium levels in the body. High potassium levels can cause muscle weakness, heart arrhythmias and/or worsening heart failure. You should avoid or limit high-potassium foods like bananas, avocados, tomatoes, potatoes and salt substitutes made with potassium.

People taking calcium channel blockers should avoid grapefruit and grapefruit juice, which can increase drug levels in the body and cause low blood pressure, reduced heart rate, headaches and dizziness.

Blood Thinners. When taking blood-thinning medications like digoxin and warfarin, there are several types of food to avoid for different reasons:

• Dark green vegetables like kale, broccoli, spinach and chard can counteract the blood-thinning effects and reduce drug effectiveness.
• Grapefruit or grapefruit juice can interfere with absorption and reduce drug effectiveness.
• Liver, eggs, cheese and cranberry juice contain high levels of vitamin K, which promotes blood clotting and counters the effect of blood thinners.
• Alcohol, garlic, ginger, onions and tomatoes can increase bleeding risk.

Immunosuppressants/Steroids. When taking immunosuppressants, including steroid medications like prednisone, avoid eating black licorice, licorice dietary supplements or any desserts that contain licorice extract. Licorice can slow the breakdown of the medication, raising levels in the bloodstream while lowering potassium, which can affect muscle function, nerve conduction and heart rhythms. Grapefruit and grapefruit juice should also be avoided for similar reasons.

People taking immunosuppressants should also avoid raw or undercooked meat, fish and eggs, unpasteurized beverages and soft cheeses. These foods are more likely to cause illness or food poisoning in those with a suppressed immune system.

Statins. Statins inhibit the production of cholesterol in the liver and promote its removal from the bloodstream. People taking statins should avoid grapefruit and grapefruit juice as they can increase drug levels in the system, leading to a greater risk for side effects like muscle pain, headache and nausea.

With or Without Food?

Most medication labels or packages will specify “take with food” or “take on an empty stomach.” It’s important to follow these recommendations carefully for effectiveness and to reduce potential side effects.

Taking medications with food may help to:

• Slow down digestion, allowing more time for the drug to be absorbed and more consistent levels in the blood.
• Reduce side effects like nausea, dizziness, stomach upset or ulcers.
• Protect medications from being destroyed by stomach acid or enzymes before they reach the intestines, where most absorption occurs.

Taking medications on an empty stomach may:

• Allow medications to be absorbed more effectively.
• Allow for faster action of drugs used for acute treatment like some pain relievers or anti-nausea drugs.

Talk to Your Doctor or Pharmacist

All medications have the potential to cause side effects, which is why it’s important to take them as directed. Those taking multiple medications should discuss potential interactions with their healthcare provider and develop a daily schedule.

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University Hospitals has a team of primary care physicians and pharmacists with the advanced training and expertise to advise patients about the medicines they are taking and how to avoid potential food interactions.