Food : Drug Interactions

A food-drug interaction can:

  • prevent a medicine from working the way it should
  • cause a side effect from a medicine to get worse or better
  • cause a new side effect
  • a medicine can also change the way your body uses a food. Any of these changes can be harmful

What else can affect how my medicines work?

Age, weight, and sex; medical conditions; the dose of the medicine; other medicines; and vitamins, herbals, and other dietary supplements can affect how your medicines work. Every time you use a medicine, carefully follow the information on the label and directions from your doctor or pharmacist.

Here are some of the most common contra-indications and their consequences. This list is not conclusive, so always check with a healthcare professional that any medications are safe to take along with any supplement that might be recommended. Remember certain foods, such as grapefruit can interact with drugs such as statins, and alcohol is not recommended with many medications.

Herb / Dietary Supplement Drugs Potential consequences / reactions
 5-Hydroxytryptophan         Fluoxetine, fluvoxamine, paroxetine, sertraline, venlafaxine   ↑ Risk of serotonin syndrome
 Acacia  Amoxicillin   ↓ Absorption of Amoxicillin
 Alfalfa  Warfarin   ↓ The effect of Warfarin
 Aloe vera  Digoxin   ↑ Digoxin toxicity
 American ginseng  Warfarin  ↓ The effect of Warfarin
 Arginine  Enalapril, Nitroglycerin   ↑ Hypotensive effects
 Arginine  Spironolactone  ↑ Risk of hyperkalemia
 Bitter orange  Phenelzine  ↑ Risk of hypertensive crisis
 Dong quai  Aspirin, Heparin, Ticlopidine, Warfarin   ↑ Risk of bleeding
 Evening primrose Warfarin  ↑ Risk of bleeding
 Garlic Ritonavir  ↓ The effect of Ritonavir
 Garlic Saquinavir  ↓ The effect of Saquinavir
 Garlic Warfarin  ↑ Risk of bleeding
 Ginkgo  Aspirin, cilostazol, clopidogrel, dipyridamole, heparin, ibuprofen, naproxen,ticlopidine, warfarin  ↑ Risk of bleeding
 Ginkgo  Risperidone  ↑ Risk of  adverse effects
 Ginkgo  Trazodone  Excessive sedation
 Glucosamine  Warfarin  ↑ Risk of bleeding
 Hawthorn  Digoxin   ↑ Digoxin toxicity
 Liquorice  Warfarin  ↑ Risk of bleeding
 l-Tryptophan Citalopram, duloxetine, fluoxetine, fluvoxamine, isocarboxazid, paroxetine, phenelzine, selegiline, sertraline, sibutramine, tranylcypromine, venlafaxin  ↑ Risk of serotonin syndrome
 l-Tryptophan  Zolpidem  ↑ Zolpidem-induced side effect
 Melatonin  Zolpidem  ↑ Sedative effects
 N-acetylcysteine  Nitroglycerin  Severe hypotension/headaches
 Niacin Atorvastatin, cerivastatin, lovastatin, rosuvastatin, simvastatin  ↑ Risk of myopathy or rhabdomyolysis
 PABA  Dapsone, sulfamethoxazole                        ↓ Antibacterial effects
 Potassium  Amiloride, benazepril, captopril, enalapril, fosinopril, indomethacin, lisinopril, moexipril, quinapril, ramipril, spironolactone, trandolapril, triamterene  ↑ Risk of hyperkalemia
 Red yeast rice  Cyclosporin ↑ Creatine phosphokinase values
 S-adenosylmethionine   Clomipramine  ↑ Risk of serotonin syndrome
 St John’s wort See below  See below
 Valerian  Alprazolam, phenobarbital  ↑ Central nervous system depression
 Vitamin A  Acitretin, bexarotene, etretinate, isotretinoin, tretinoin  ↑ Risk of Vitamin A toxicity
 Vitamin B6 Altretamine  ↓ Response to altretamine


 St John’s wort alters the effects of the following drugs

Drugs Potential consequences / reactions

Bupropion, buspirone, eletriptan, meperidine, trazodone

MAOI: isocarboxazid, phenelzine, tranylcypromine

SSRI: citalopram, duloxetine, fluoxetine, fluvoxamine, nefazodone, paroxetine, sertraline, venlafaxine

TCA: amitriptyline, amoxapine, clomipramine, desipramine, doxepin, imipramine, nortriptyline, protriptyline, trimipramine

 ↑ Risk of serotonin syndrome
 Fentanyl, Morphine, Oxycodone   ↑ Sedation
 Lidocaine , Propofol, sevoflurane  ↑ Risk of cardiovascular collapse
 Piroxicam, rasagiline, risperidone, tetracycline, tolbutamide, tretinoin  ↑ Photosensitivity reactions


St John’s wort reduces the effects of the following drugs


Benzodiazepine: alprazolam, clonazepam, diazepam, midazolam,triazolam; Busulfan; Calcium channel blockers: diltiazem, felodipine, nicardipine, nifedipine, nitrendipine,verapamil; Carbamazepine;  Cyclophosphamide; Cyclosporin; Dapsone; Dexamethasone; Digoxin; Docetaxel; Dolasetron; Doxorubicin; Erlotinib; Erythromycin; Estrogens ⁄ progestogens: estradiol, gestodene, levonorgestrel, norethindrone ; Etoposide; Exemestane; Fexofenadine; Finasteride; Flutamide; Gliclazide;  

Haloperidol; Ifosfamide; Imatinib; Irinotecan; Ivabradine; Ixabepilone; Lapatinib; Loperamide; Maraviroc; Mephenytoin

Methadone; NNRTI: delavirdine, efavirenz, nevirapine; Omeprazole; Ondansetron; Paclitaxel; Phenprocoumon; Phenytoin;

Protease inhibitors: amprenavir, atazanavir, darunavir, fosamprenavir, indinavir, nelfinavir, ritonavir, saquinavir, tipranavir ;

Quetiapine ; Quinidine ; Sildenafil ; Sirolimus ; Sunitinib ; Tacrolimus ; Tamoxifen ; Temsirolimus ; Teniposide ; Tramadol

Vinblastin ; Vincristine; Voriconazole; Warfarin

Amended from-Tsai HH, Lin HW, Simon Pickard A, Tsai HY, Mahady GB. Evaluation of documented drug interactions and contraindications associated with herbs and dietary supplements: a systematic literature review. International journal of clinical practice. 2012 Nov;66(11):1056-78.