Document name:
Food and medicines communication.
Version 2
Portfolio
Document type:
Medicines Management
Communication
Staff group to whom it
applies:
All prescribers, pharmacy and clinical
staff within the Trust
Distribution:
The whole of the Trust
How to access:
Intranet
Ward folders
Issue date:
Date of issue
October 2005
Reviewed
October 2008
August 2012
Date of review
July 2015
Next review:
Approved by:
Drug and Therapeutics Sub
Committee
Developed by:
Kate
Dewhirst,
Deputy
Chief
Pharmacist on behalf of the Drug and
Therapeutics Sub Committee
Director leads:
Medical Director
Contact for advice:
Kate Dewhirst, Deputy Chief
Pharmacist
Drug and Therapeutics Trust Action Group
Communication
Food and Medicines – Version 2
Introduction
Some foods and drinks may affect the way in which the body handles medicines and
therefore have the potential to either decrease or increase a medicine’s therapeutic or
adverse effects. This may be important but often with medication that is taken long term the
key is to maintain regular regimens; take at regular times in relation to meals; keep the diet
balanced with no sudden changes in carbohydrate, salt or fat content, unless instructed to do
so by a registered dietician. In addition medicines can affect food handling and so influence
nutritional state.
Some interactions may be mechanical; some may be pharmacokinetic, decreasing clearance
or metabolism of the medicine. Medication with a narrow therapeutic index may be more
significantly affected.
Clinically significant interactions
Food
Medication
Presence of any
Antibiotics such as
food in stomach
ampicillin,
flucloxacillin and
erythromycin
Salt (sodium
chloride)
Lithium
Milk and
indigestion
remedies
Iron, tetracycline,
digoxin, etidronate
and alendronate,
quinolones such as
ciprofloxacin
Carbamazepine
Statins such as
simvastatin and
atorvastatin
Calcium channel
blockers such as
nifedipine
Ciclosporin
Benzodiazepines
such as diazepam,
and midazolam
Antiretrovirals
Anticancer agents
Amiodarone
Grapefruit and
grapefruit juice
Effect
Stomach acid
destroys the
antibiotic. Absorption
can also be reduced
Increased intake of
salt leads to
increased excretion
of lithium and
reduced effect.
Decreased intake
conversely causes
increased effect and
toxicity
Reduced absorption
Inhibits liver enzymes
(CYP 3A4) leading to
accumulation in the
body, increased side
effects and the
emergence of toxic
effects. It can reduce
or improve
absorption and hence
efficacy
Comments/management
Take an hour before food or on
an empty stomach.
Amoxicillin is unaffected. Some
are available as enteric coated
tablets
Maintain regular diet. Take care
with antacids that contain
sodium. Avoid dehydration,
which causes loss of salt and so
increased lithium levels. Be
aware of signs of toxicity.
Allow a two-hour gap either side
of the dose.
AVOID the fruit and juice at all
times.
As little as one glass of juice
can cause increased levels and
the effects can last for three
days. The effects vary from
person to person and from one
brand of juice to another. The
results are unpredictable. Sour
oranges such as Seville
oranges may have a similar
effect
Fermented foods
containing
tyramine eg
mature cheese,
red wine, soy
sauce
Cranberry Juice
Monoamine
Oxidase inhibitor
(MAOIs)
antidepressants
Sudden serious rise
in blood pressure
Warfarin
Increased and
unstable INR and
bleeding
High fibre foods
Green vegetables
such as broccoli,
sprouts and
cabbage
Digoxin
Warfarin
Charcoal grilled
food ie barbeque
food
Warfarin,
Theophylline
Carbohydrate/
protein balance
Theophylline
Reduced absorption
Stimulate metabolic
enzymes leading to
reduce anticoagulant
efficacy. They also
contain large amount
of Vitamin K, which
antagonises the
action of warfarin.
Enzyme induction
can lead to reduced
efficacy. Reduced
INR and worsening
asthma
Due to high plasma
protein binding.
Fasting (religious
or pre-procedure,
AVOID these foods. Study the
information supplied with the
medication or consult a
pharmacist or dietician.
Avoid large quantities of these
foods with reversible MAOIs
AVOID (it is not known if other
cranberry products such as
capsules or concentrates have
the same effect so caution is
required with these)
No sudden changes in diet
Eat in moderation and make no
sudden changes in diet once
stabilised. Avocado and ice
cream (in large quantities have
also been implicated.)
Eat in moderation and make no
sudden changes in diet once
stabilised. Ordinary grilled food
is safer
Maintain a balanced diet.
A high protein diet (e.g. Atkins)
increases metabolism and
decreases efficacy. High
carbohydrate diet slows
theophylline metabolism and the
risk of toxicity of the medication
is increased.
Medicines taken
under fasting
conditions may be
absorbed more
rapidly and onset of
action may be more
rapid.
Recommendations
 Alert those taking the medication listed above to the potential dietary effects on
treatment.
 Be alert for adverse drug reactions or worsening symptom control in those who
have lost or gained a lot of weight.
 Remember alcohol interacts with CNS depressants and excess caffeine
consumption can mimic many psychiatric conditions
References
P.Mason. Food-Drug Interactions. Pharmaceutical Journal 2002; 29: 571-573
BNF 50 September 2005
MHRA/CSM. Current problems in pharmacovigilance. 2004; 30:2
MHRA/CSM. Current problems in pharmacovigilance. 2004; 30:10
A McLAchlan et al. Meals and medicines. Australian Prescriber 2006:28(2) 40-42