Skip to content
ppharmaranks
Menu
CompaniesProductsDrug classesConditionsBest by conditionTreatmentsInteraction checkerFood & medicinesWhat pharmacies payPill identifierMedicines & breastfeedingChildren’s dosage chartsDo medicines expire?Crushing & splitting pillsHow long meds take to workAlternating Tylenol & ibuprofenDrug recallsSupplementsSafety & lawsuitsGuidesA–ZHow we rate

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”.

By the pharmaranks editorial teamReviewed against FDA drug labels, USDA FoodData Central & the NIH Office of Dietary Supplements sourcesHow we research
Grapefruit and medications: which drugs it actually affects (simvastatin yes, pravastatin no), why, and what to do — the FDA-cited list.Tyramine and MAOIs:the aged/fermented foods that can trigger a blood-pressure crisis — and the MAOIs and doses that don’t need the diet. From the FDA label.Drugs and alcohol: what the FDA label actually says about drinking on each medicine — the dangerous combinations to avoid, and the ones that are only a caution.Caffeine and your medications:the short, specific list that actually interacts (CYP1A2 drugs, and the stress-test caffeine can defeat) — not “coffee is bad with everything.”

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. For ciprofloxacin the FDA label is specific: take it at least two hours BEFORE, or six hours AFTER, anything containing calcium, iron, magnesium or aluminium — the after-gap is the long one, and it is the one that gets missed. Levofloxacin and the tetracyclines run about two hours either side. 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 four hours away from levothyroxine, and — per the FDA label for ciprofloxacin — two hours before or six hours after a fluoroquinolone; about two hours either side for the tetracyclines. 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 →

Magnesium

Food magnesium is rarely the problem; a magnesium-containing ANTACID or laxative is. Milk of Magnesia, Maalox, Mylanta, Rolaids and many 'calcium-magnesium' supplements are concentrated magnesium — swallow one at the same time as your antibiotic and you can cancel the dose. Per the ciprofloxacin FDA label, take the fluoroquinolone at least two hours BEFORE, or six hours AFTER, anything with magnesium, calcium, iron or aluminium; the tetracyclines run about two hours either side; oral bisphosphonates and levothyroxine want a clear empty-stomach window of their own. Separate them in time and you keep both.

12foods, per serving →

Vitamin B12

This is not a reason to stop metformin or your reflux drug — both are doing important jobs, and the fix is monitoring, not avoidance. If you have taken either for years, ask your prescriber to check a B12 level (the metformin label itself recommends it), especially if you feel unusually tired or have numbness or tingling in the hands or feet. B12 from food or a supplement corrects a deficiency; you do not have to choose between the medicine and your B12.

11foods, per serving →

Sodium

The rule for lithium is not low-salt or high-salt — it is STEADY salt. Pick a sodium habit and keep it consistent, and tell whoever manages your lithium before you start a diet, a cleanse, or a new exercise routine that makes you sweat. Be extra careful during vomiting, diarrhoea, or fever: fluid and sodium loss can raise lithium fast, and that is exactly when a level should be checked. NSAIDs (ibuprofen, naproxen) and some blood-pressure drugs also raise lithium levels — this is a drug to manage with a prescriber, not a web page.

11foods, per serving →

Protein

The mistake is to read this as "eat less protein". Protein is not optional — people with Parkinson's are already at risk of losing weight and muscle, and cutting it does real harm. What changes is TIMING: levodopa is commonly taken 30 to 60 minutes before eating, and some people are advised to shift most of their protein into the evening meal so the daytime doses work cleanly. That is a plan to make with a neurologist, not from a table. Protein shakes count, and so does milk in coffee.

18foods, per serving →

Fibre

Do not cut fibre to make your thyroid medicine work better. Fibre is doing more for your health than the few micrograms at stake, and the fix is separation, not subtraction: levothyroxine is taken on an empty stomach, well before a high-fibre breakfast. The genuinely important moment is when you START or STOP a fibre supplement such as psyllium — that shifts absorption enough to matter, so tell your prescriber, because your dose may need re-checking rather than your diet.

19foods, 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.

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.