Food and your medicines
Most “foods to avoid” advice on the internet is written by people who have never read a drug label. These pages are the other way round: the interaction comes from the FDA label, the amounts come from USDA FoodData Central, and each one leads with the thing people actually get wrong — which is usually the opposite of “avoid it”.
Vitamin K
The instinct is to avoid greens. That is the wrong move, and the FDA label does not ask for it. What matters is CONSISTENCY: eat roughly the same amount of vitamin K each week so your dose can be matched to it. A person who eats a cup of spinach most days is far easier to anticoagulate than one who swears off greens and then has a salad at a wedding. Talk to whoever manages your INR before changing your diet — in either direction.
12foods, per serving →
Potassium
The danger is almost never the banana. It is the SALT SUBSTITUTE. Products sold as 'NoSalt', 'Nu-Salt' or 'lite salt' are potassium chloride — a teaspoon can carry more potassium than any food on this list, and people on blood-pressure drugs are precisely the people told to cut sodium, so they reach for it. Ask your prescriber before using one, and before taking a potassium supplement. Do not stop eating vegetables on the strength of a web page.
15foods, per serving →
Calcium
Nobody has to give up dairy. What matters is SPACING. Levothyroxine is taken on an empty stomach, and calcium — from food, a supplement, or an antacid — should be kept about four hours away from it. Antibiotics need a couple of hours' clearance. The most common way this goes wrong is not a glass of milk: it is a calcium supplement or a Tums swallowed at the same time as the pill, which is the one thing to stop doing.
13foods, per serving →
Iron
Food iron is rarely the problem; an iron TABLET taken alongside your other pills is. Keep iron supplements a few hours away from levothyroxine and from tetracycline or fluoroquinolone antibiotics. And if you are taking iron for anaemia, the tea or coffee you swallow it with is working against you — vitamin C helps, tannins hurt.
12foods, per serving →
Every food interaction we track
These appear on the page of every drug they apply to, matched by the drug’s FDA pharmacologic class or its active ingredient — not by guesswork.
Vitamin K–rich foods
You don't have to avoid these foods — the key is keeping your intake steady week to week rather than suddenly eating a lot more or less. Tell your clinician before making big diet changes.
Warfarin — MedlinePlus (U.S. National Library of Medicine) ↗Tyramine-rich foods
Follow the specific food list your prescriber gives you and avoid high-tyramine foods while taking an MAOI (and for a period after stopping). Seek urgent care for a sudden severe headache.
Phenelzine (an MAOI) — MedlinePlus (U.S. National Library of Medicine) ↗Dairy, calcium, iron & antacids
Separate the antibiotic from dairy, supplements, and antacids by a couple of hours — take it at the interval the label or your pharmacist specifies.
Tetracycline — MedlinePlus (U.S. National Library of Medicine) ↗Alcohol
Avoid alcohol while taking it and for a few days after your last dose, as your prescriber or the label directs. Alcohol can hide in some liquid medicines and mouthwashes.
Metronidazole — MedlinePlus (U.S. National Library of Medicine) ↗Potassium-rich foods & salt substitutes
Don't use potassium-based salt substitutes unless your clinician approves, and ask before taking potassium supplements. Your clinician may check your potassium level with blood tests.
Lisinopril (an ACE inhibitor) — MedlinePlus (U.S. National Library of Medicine) ↗Grapefruit & grapefruit juice
Avoid grapefruit and grapefruit juice with this medicine unless your pharmacist or the label says it's fine — check, because not every drug in a class is affected the same way.
Grapefruit Juice and Some Drugs Don't Mix — U.S. FDA ↗
General information, not medical advice. Never change your diet or your dose on the strength of a web page — for anticoagulants in particular, a sudden change in either direction is the risk. Talk to whoever manages your treatment.