Allergic Reactions to Sulfites (sulphite
allergy)
How do they work?
Sulfites release sulphur dioxide, which is the active component
that helps preserve food and medication.
Asthmatic reactions are the most common adverse effect
The most common adverse reaction with exposure to sulfites,
is that of asthma like symptoms, estimated to occur in 5 to 10%
of patients with asthma. These symptoms are more likely to occur
in patients with severe asthma, or those in whom asthma is poorly
controlled. Reactions can be mild through to life-threatening.
Anaphylactic reactions are much less common
Occasional patients exposed to sulfites, will experienced
symptoms similar to anaphylaxis with flushing, fast heartbeat,
wheezing, hives, dizziness, stomach upset and diarrhoea, collapse,
tingling or difficulty swallowing.
The mechanism by which reactions occur is unclear
The mechanism by which some people react to sulfites another
don't, is not clear. sulphur dioxide is an irritant, and so reflex
contraction of the airways has been proposed as one possible reason
why asthma like responses may occur. This mechanism may be particularly
important when sulfites are ingested in the form of liquid like
beer or wine, when sulphur dioxide given off by the liquid inhaled
during the swallowing process. Some asthma patients reacting to
sulfites, have a partial enzyme deficiency (sulfite oxidase) that
can help break down sulphur dioxide. Occasional patients (but
not many) will have positive skin allergy tests to sulfites as
well, and so true allergic reactions to sulfites may also occur
in some people.
Diagnosis of suspected sulfite sensitivity
History -- the possibility of adverse reaction to sulfites,
can be suspected when symptoms occur after potential sources of
exposure to these substances.
Allergy tests -- the vast majority of people with sulfites
sensitivity, will not have positive allergy tests. There is currently
no reliable blood or skin allergy test for these patients.
Challenge -- at times, it may be important to do a deliberate
challenge with sulfites in a graded fashion under medical supervision,
in patients with suspected sulfites sensitivity. These challenges
may be performed to prove or disprove sensitivity.
Potential sources of dietary exposure to sulfites
Sulfites have a useful role to play in helping preserve many
foods and beverages. The addition of sulfites to some foods like
beer and wine is permitted in most countries. In many countries,
it is illegal to add these to foods like fresh salads or fruit
salads, or to meats like mincemeat. Unfortunately, these can be
added from time to time illegally. The following is a list of
the most common sources of accidental exposure to sulfites.
Drinks -- cordials and some fruit juices as well as
beer and wine. Occasionally soft drinks. Instant tea.
Other liquids -- commercial preparations of lemon and lime
juice, vinegar, grape juice.
Commercial foods -- dry potatoes, some gravies and sauces
and fruit toppings, maraschino cherries, pickled onions, Maple
syrup, jams, jellies, some biscuits and bread or pie or pizza
dough
Fruit -- dried apricots, and sometimes grapes will be transported
with sachets of the sulfite containing preservative. Dryness of
tightness do not normally contain sulfites.
Salads and fruit salads -- sometimes restaurant salads
and fruit salads will have sulfites added to preserve their colour.
Crustaceans -- sulphur powder is sometimes added over the
top of crustaceans to stop them this colouring.
Meat -- sulfites are sometimes added illegally to mincemeat
or sausage meat.
Other foods -- gelatin, coconut
The presence of sulfites can be recognised on labelled food
By Australian law, the presence of sulfites must be indicated
on the label by code numbers 220 to 228, or the word "sulfite".
220 -- sulphur dioxide
221 -- sodium sulfite
222 -- sodium bisulfite
223 -- sodium metabisulfite
224 -- potassium metabisulfite
226 -- calcium sulfite
227 -- calcium and bisulfite
228 -- potassium bisulfite
Low /no sulfite wines
As a rule, sulfites are found at higher levels in the cask
wine than bottled wine, and are at much higher concentrations
in white wine than red wine, when natural tannins help preserve
the beverage. Some winemakers in Australia produce wines and state
that they do not add sulfites into the wine. There are various
technical reasons related to winemaking why very low levels of
sulfites might still be present, even when not added to the wine
itself. The author has not personally verified the claims of being
preservative free. Those interested should make inquiries of the
winemaker. The following Australian winemakers produce low / no
sulfite wines. This listing is for information purposes only,
is not exhaustive, should not be interpreted as a recommendation,
and no payment of any kind has been received by the author for
this listing.
Low / no sulfite beers
Some brewers produce beer and state that they do not add sulfites.
There are various technical reasons why very low levels of sulfites
might still be present, even when not added to the product itself.
The author has not personally verified the claims of being preservative
free. Those interested should make inquiries of the brewery. The
following brewers claim to produce low / no sulfite beers. This
listing is for information purposes only, is not exhaustive, should
not be interpreted as a recommendation, and no payment of any
kind has been received by the author for this listing.
Sulfites are also used in some medications
Topical -- some eyedrops and creams will contain sulfites.
Oral medication -- to the knowledge of this author, no
adverse reactions to sulfites have occurred from swallowed medication
that might have been contaminated with sulfites.
Injectable medication -- this is the most likely source
of exposure. Adrenaline (epinephrine), isoprenaline, phenylephrine,
dexamethasone and some other injectable corticosteroids, dopamine,
local anaesthetics/dental anaesthetics containing adrenaline,
some anaesthetic agents (eg. propofol) and aminoglycoside antibiotics
are the most common potential sources of exposure. It should be
noted however, that even in patients with sulfite sensitivity,
it is generally considered that adrenaline should not be withheld
if needed, as the benefit of adrenaline is considered to outweigh
any theoretical risk from sulfites sensitivity in an emergency
situation.
Management of sulfite sensitivity
Time -- there is no evidence that sulfites sensitivity
reduces with time
Avoidance -- this is the mainstay of management. Commercial
test strips to test food for the presence of sulfites are available
in some other countries, but to the knowledge of the author, not
in Australia. These are also not 100% reliable.
Switching off the sensitivity -- there is no proven way
of desensitisation or immunotherapy to reduce the severity of
sulfites sensitivity.
Emergency action plan -- those with relatively mild reactions
like mild wheezing, should carry their asthma puffers when eating
away from home. Those with more serious reactions akin to anaphylaxis,
are managed along the same lines as anyone else with anaphylaxis,
with provision of an emergency action plan, and trained in the
use of injectable adrenaline such as EpiPen.
Sensitivity to sulfites is a different condition to sulphur
drug allergy
Some patients will have allergic reactions to sulphur molecule
containing medication or sulphur antibiotics. This is a very different
condition to sulfite sensitivity. Those allergic to sulfites are
not at increased risk of sulphur drug allergy, and vice versa.
See link
for more information.
Web links
Food Standards Australia New Zealand
Allergy Society of South Africa (ALLSA)
Allergy Resources International
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