Everyone wants to be an instant expert ... the truth is that wisdom relies on a good knowledge base and having experience with the data. My own INR journey has been 13 years and built on solid foundations; but I do not call myself an expert, just well informed.
in my country the recommendations for patients look something like this, and this list already makes me feel uneasy
I am sending you a memo on the interaction of warfarin with medications and food products:
It is not recommended to start or stop taking other medications or change the doses of medications taken without consulting your doctor.
When co-administered, the effects of discontinuing induction and/or inhibition of warfarin action by other drugs must also be taken into account.
The risk of developing severe bleeding increases with the simultaneous use of warfarin with drugs that affect platelet levels and primary hemostasis: acetylsalicylic acid, clopidogrel, ticlopidine, dipyridamole, most NSAIDs (except COX-2 inhibitors), penicillin antibiotics in high doses.
Also, the combined use of warfarin with drugs that have a pronounced inhibitory effect on cytochrome P450 isoenzymes (including cimetidine, chloramphenicol) should be avoided, since the risk of bleeding increases when taken for several days. In such cases, cimetidine can be replaced, for example, with ranitidine or famotidine.
The effect of warfarin may be enhanced by concomitant use with the following drugs: acetylsalicylic acid, allopurinol, amiodarone, azapropazone, azithromycin, alpha and beta interferon, amitriptyline, bezafibrate, vitamin A, vitamin E, glibenclamide, glucagon, gemfibrozil, heparin, grepafloxacin, danazol, dextropropoxyphene, diazoxide, digoxin, disopyramide, disulfiram, zafirlukast, indomethacin, ifosfamide, itraconazole, ketoconazole, clarithromycin, clofibrate, codeine, levamisole, lovastatin, metolazone, methotrexate, metronidazole, miconazole (including in the form of an oral gel), nalidixic acid, norfloxacin, ofloxacin, omeprazole, oxyphenbutazone, paracetamol (especially after 1-2 weeks of continuous use), paroxetine, piroxicam, proguanil, propafenone, propranolol, influenza vaccine, roxithromycin, sertraline, simvastatin, sulfafurazole, sulfamethizole, sulfamethoxazole/trimethoprim, sulfaphenazole, sulfinpyrazone, sulindac, steroid hormones (anabolic and/or androgenic), tamoxifen, tegafur, testosterone, tetracyclines, thienyl acid, tolmetin, trastuzumab, troglitazone, phenytoin, phenylbutazone, fenofibrate, feprazone, fluconazole, fluoxetine, fluorouracil, fluvastatin, fluvoxamine, flutamide, quinine, quinidine, chloral hydrate, chloramphenicol, celecoxib, cefamandole, cephalexin, cefmenoxime, cefmetazole, cefoperazone, cefuroxime, cimetidine, ciprofloxacin, cyclophosphamide, erythromycin, etoposide, ethanol.
Preparations of some medicinal plants (official or unofficial) can also either enhance the effect of warfarin: for example, ginkgo (Ginkgo biloba), garlic (Allium sativum), angelica (Angelica sinensis), papaya (Carica papaya), sage (Salvia miltiorrhiza); or reduce it: for example, ginseng (Panax ginseng), St. John's wort (Hypericum perforatum).
Warfarin and any St. John's wort preparations should not be taken simultaneously, and it should be taken into account that the induction effect of warfarin action may persist for another 2 weeks after stopping St. John's wort preparations. If the patient is taking St. John's wort preparations, the INR should be measured and the preparation should be stopped. Monitoring of the INR should be careful, as its level may increase when St. John's wort is discontinued. Warfarin can then be prescribed.
Quinine, which is found in tonic drinks, can also enhance the effects of warfarin.
Warfarin may enhance the effects of oral sulfonylurea hypoglycemic agents.
The effect of warfarin may be weakened when used concomitantly with azathioprine, aminoglutethimide, barbiturates, valproic acid, vitamin C, vitamin K, glutethimide, griseofulvin, dicloxacillin, disopyramide, carbamazepine, cholestyramine, coenzyme Q10, mercaptopurine, mesalazine, mianserin, mitotane, nafcillin, primidone, retinoids, ritonavir, rifampicin, rofecoxib, spironolactone, sucralfate, trazodone, phenazone, chlordiazepoxide, chlorthalidone, cyclosporine.
The use of diuretics in cases of pronounced hypovolemic action can lead to an increase in the concentration of coagulation factors, which reduces the effect of anticoagulants.
In case of combined use of warfarin with other drugs listed below, it is necessary to monitor INR at the beginning and end of treatment, and, if possible, 2-3 weeks after the start of therapy.
Foods rich in vitamin K reduce the effect of warfarin; decreased absorption of vitamin K due to diarrhea or laxatives potentiates the effect of warfarin. Green vegetables contain the highest levels of vitamin K, so when taking warfarin, the following foods should be consumed with caution: amaranth greens, avocados, broccoli, Brussels sprouts, cabbage, canola oil, chayotes, onions, coriander, cucumber peel, chicory, kiwi fruit, lettuce, mint, mustard greens, olive oil, parsley, peas, pistachios, red seaweed, spinach greens, spring onions, soybeans, tea leaves (but not tea-based drinks), turnip greens, and watercress.