Some of the most well-known food-drug interactions include the blood thinner warfarin (brand names Jantoven and Coumadin) and foods containing vitamin K, such as broccoli, cabbage, kale, spinach, Swiss chard , seaweed and other leafy greens. Some vegetable oils also contain high amounts of K. These vegetables can reduce the effectiveness of commonly prescribed medications, inhibiting its ability to stop or prevent blood clotting, says Dima Qato, associate professor at the University of Southern California School. of Pharmacy and Senior Fellow at the Schaeffer Center for Health Policy & Economics at USC.

Before completely getting rid of these foods, ask your doctor if you should avoid them (or any others) while taking warfarin, or if you can eat moderate amounts of them regularly. Some experts now advise people taking warfarin to be very consistent with the amount of vitamin K they get through food, avoiding large amounts at a time. So, “If you like salad, eat it three times a week and the same amount each time,” advises Brown, and your warfarin concentration should stay stable.

3. Deli meats, soy, other foods containing tyramine, plus MAOIs

An older class of antidepressants called monoamine oxidase inhibitors (MAOIs) can have dangerous interactions with foods that contain high levels of the amino acid tyramine. Taking MAOIs and eating foods high in tyramine can lead to high levels of tyramine in the body, which can trigger a sudden and dangerous increase in blood pressure. Foods high in tyramine include smoked and cured meats, aged cheeses, fermented foods, red wine, some draft beers, soy products (soy sauce, miso, tofu), and very ripe bananas. These days, MAOIs aren’t used as frequently to fight depression, but they are sometimes used to treat Parkinson’s disease. If you’re taking an MAOI, it’s best to avoid these foods, says Brown. You can also ask your doctor for a complete list of dietary restrictions.

4. Grapefruit and cholesterol lowering

Consuming grapefruit or grapefruit juice may inhibit an enzyme needed to metabolize statins, Qato warns. As a result, “the drug stays in the blood and builds up, increasing the risk of side effects such as muscle aches.”

Of the statins, atorvastatin, lovastatin, and simvastatin (common brands Lipitor, Altoprev/Mevacor, and Zocor) are the most problematic when it comes to grapefruit juice. To be on the safe side, patients are often advised to avoid grapefruit and grapefruit juice altogether when taking statins, Qato says.

Grapefruit can also cause problems when mixed with other medications. A few include certain anti-anxiety medications, such as BuSpar, and certain corticosteroids that treat Crohn’s disease or ulcerative colitis, such as Entocort EC and Uceris tablet (both budesonide), according to the U.S. Food and Drug Administration.

5. Bananas and Other Potassium-Rich Foods Plus ACE Inhibitors

If you take blood pressure lowering ACE inhibitors with foods high in potassium, including bananas, avocados, tomatoes, and dried apricots, you may get high levels of potassium in your body, which can lead to heart arrhythmias potentially dangerous, warns Brown. That’s why it’s wise to limit your intake of potassium-rich foods while taking an ACE inhibitor. It is recommended that you take some ACE inhibitors, such as captopril and moexipril (brand names Capoten and Univasc), at least one hour before meals.

6. Fruit juices and some antihypertensives/antihistamines

If you’re taking a calcium channel blocker (another type of blood pressure medication), avoid grapefruit juice because it can make the drug ineffective, says Qato. Also, if you are taking the beta-blocker atenolol (Tenormin) or the renin blocker aliskiren (Tekturna), you should be aware that drinking apple juice or orange juice may decrease levels of the drug in your body. .​

In a lesser-known interaction, some of the newer generation antihistamines, namely fexofenadine (Allegra), can also interact with acidic juices, such as apple juice, orange juice, and grapefruit juice, says Qato. . “These acidic juices could affect absorption and neutralize the effect of antihistamines so they don’t really work.” If you’re looking for allergy relief, Qato advises avoiding these juices within two to four hours of taking one of these antihistamines.

7. High fiber foods and levothyroxine, digoxin

Eating soy flour, nuts, and other fiber-rich foods may make levothyroxine — a drug listed under several brand names used to treat an underactive thyroid gland — less effective. The same is true if you are taking digoxin, which is sold under several brand names and is used to treat heart failure. High-fiber foods can affect a person’s absorption of the drug, Qato says, so your best bet is to take digoxin at least two hours before or after consuming high-fiber meals or snacks.