Family doctor

Food can affect some medicines. Therefore often your medicine label may note "take with food", "take on an empty stomach" or "take half an hour before food". For many medicines that you take every day it is best to take them at the same time in relation to food every day.

Common instructions about medicines and foods and usual explanations are as follows:

Take with food.

• In most cases the medicine can be taken during the meal or immediately after the meal.
• There may be two reasons for this instruction, either:
• The medicine can cause a stomach upset if you take it without food (e.g. doxycycline, Augmentin), or
• Food will make the medicine be absorbed better into the body (e.g. griseofulvin)

Take after food.

This may be for the same reasons as take with food. In the case of Gaviscon, it is used after food so that it works better to stop the food coming up from the stomach into the oesophagus (gullet).

Take on an empty stomach.

• In most cases the medicine should be taken at least two hours after the last time you ate and at least one hour before you are going to eat again.
• Examples include flucloxacillin, and antibiotic that doesn't work nearly as well if you have it with food, and etidronate (Didronel).
• This instruction is because the medicine is not absorbed as well by the body if you have much food in your stomach. In some cases the medicine may bind with something in the food. In other cases there is a special coating (enteric coating) on the tablet that does not dissolve until it gets into the intestine, so if you take the medicine with a big meal it can take many hours to start working (e.g. anti-inflammatories with an enteric coating).
• Medicines generally work faster if taken on an empty stomach, so some pain relievers may be recommended to be taken before food.

Do not take grapefruit or grapefruit juice while taking this medicine.

• In the last couple of years grapefruit have been found to alter the levels of some medicines in the body. In some cases the amount of the medicine in the blood can be increased by as much as 16 times the usual amount. So, if this instruction is on the label of your medicine you are best to avoid grapefruit and grapefruit juice completely.
• Enzymes in the wall of the gut change some medicines on the way through into the bloodstream, making them less active. Grapefruit juice blocks these enzymes so medicines that would normally be changed instead arrive intact in the bloodstream in greater amounts than expected.

Avoid certain foods with this medicine.

Monoamine oxidase inhibitors such as tranylcypromine (Parnate) or phenelzine (Nardil) have special instructions with respect to foods. Many foods need to be avoided including cheese, sour cream, yeast and meat extracts, liver, sherry, beer (even non-alcoholic), red wine, avocados, chocolate, soy beans, broad bean pods, meals prepared with tenderisers, pickled fish, canned figs. Your pharmacist or doctor will be able to give you a more complete list.

Common medicines taken with food

 Anti-diabetics such as glibenclamide and metformin

Anti-inflammatories or NSAIDs (e.g. Voltaren, Naprosyn), unless enteric coated, or a quick effect is required.

Steroids e.g. prednisone, prednisolone, hydrocortisone

 Adalat (nifedipine)

Augmentin (amoxicillin + clavulanic acid)

Aspirin in high doses

Daonil (glibenclamide)

Diamicron (gliclazide)

Epilim (sodium valproate)

EES (erythromycin ethyl succinate)

Fergon (iron)

Ferrogradumet (iron)

Flagyl (metronidazole)

Glucophage (metformin)

Lanoxin (digoxin)

Lithicarb (lithium)

Megostat (megestrol)

Minidiab (glipizide)

Mino-tabs (minocycline)

Naprosyn (naproxen)

Nifuran (nitrofurantoin)

Nolvadex (tamoxifen)

Nuelin (theophylline)

Priadel (lithium)

Roaccutane (isotretinoin)

Salazopyrin (sulphasalazine)

Slow K (potassium)

Sporanox (itraconazole)

Theo-dur (theophylline)

Vermox (mebendazole)

Vibra-tabs (doxycycline)

Voltaren (diclofenac)

Zinc

Zyloprim (allopurinol)

 Common medicines taken on an empty stomach

 Capoten (captopril)

Didronel (etidronate)

ERA (erythromycin stearate)

ERYC (erythromycin base)

Floxapen (flucloxacillin)

Selectol (celiprolol)

 Examples of medicines that don't mix well with grapefruit juice

 Halcion (triazolam)

Isoptin (verapamil)

Plendil (felodipine)

Prepulsid (cisapride)

Zocor (simvastatin)

Note: This list does not include all medicines, and in some cases recommendations may differ country to country. Follow the instructions of your pharmacist or doctor.