Shellfish and fish allergies
Shellfish and fish allergies
About shellfish and fish allergies
Allergies to shellfish and
fish
are more common in adults and adolescents than in young children. It is estimated that one in every 100 people has a seafood allergy.
The types of seafood that can cause allergies include scaly fish and shellfish, including molluscs (such as oysters, mussels and squid) and crustaceans (such as prawns, crayfish and yabbies).
Symptoms of fish or shellfish allergies vary and range from mild reactions to a
severe allergic reaction (anaphylaxis)
. The most common symptom is raised red bumps of skin (
hives
). Other symptoms include wheezing and trouble breathing, cramps, nausea or vomiting.
The best way to manage a shellfish or fish allergy is to avoid all food containing the species to which you are allergic.
Food allergies can be life threatening. If you, or someone in your care, have a severe allergic reaction (anaphylaxis), call triple zero (000) for an ambulance. Administer an injection of adrenaline (epinephrine) into the outer mid-thigh. The person having the reaction should not stand or walk. Further doses of adrenaline may be given if there is no response after 5 minutes. Give adrenaline first, then asthma reliever puffer, if required.
Symptoms of shellfish and fish allergies
Every person’s
immune system
is different, and shellfish and fish allergies can cause diverse symptoms, ranging from mild to severe. Many food allergies do not cause severe symptoms, but they can be life threatening in some people and should be taken seriously.
Fish and shellfish allergic reactions can occur after eating seafood, but you can also have symptoms after touching seafood or inhaling fumes from shellfish or fish while they are being cooked or processed in a factory.
Milder allergic symptoms that can occur before a severe allergic reaction include:
raised red bumps of skin –
hives
(urticaria)
swelling of the lips
tingling of the throat and mouth
itchy skin and rash
runny nose
tightening of the throat
stomach pain, vomiting (these are signs of anaphylaxis for
insect allergy
).
If you or a child in your care have experienced any of these symptoms after eating fish or shellfish, the risk of having a severe reaction after eating that food is greater than usual.
Ask your doctor to refer you to a
clinical immunology/allergy
specialist
External Link
. They will confirm the diagnosis, prescribe an adrenaline injector (EpiPen® or Anapen®) and give you an
Australasian Society of Clinical Immunology and Allergy (ASCIA) Action Plan for
Anaphylaxis
External Link
for the brand of injector prescribed.
Keep a record of your symptoms
Diagnosing an allergy can be difficult. If you think you or a child in your care may have an allergy, keeping a record of symptoms can help you and your doctor to understand what is causing them.
Your diary could include information about whether the symptoms occur:
inside your home, outside or both
for a short time or longer
at night, during the day or when you wake up
after you have had a particular food or drink
after you have taken a particular medication, either prescription or over the counter from a pharmacy or supermarket
after you have taken a
herbal medicine
.
Severe allergic reaction – anaphylaxis
A
severe allergic reaction (anaphylaxis)
is life threatening.
Symptoms of a severe allergic reaction include:
difficult or noisy breathing
swelling of the tongue
swelling or tightness of the throat
difficulty talking or a hoarse voice
wheeze or persistent cough
persistent dizziness or collapse
paleness and floppiness in young children.
If you, or someone in your care, have a severe allergic reaction (anaphylaxis), call triple zero (000) for an ambulance. Do not allow the person having the reaction to stand or walk. Administer adrenaline into the outer mid-thigh via injector (EpiPen® or Anapen®), if available. Further doses may be given if there is no response after 5 minutes. Give adrenaline first, then asthma reliever puffer, if required.
Causes of shellfish and fish allergies
For all
allergies
, the immune system reacts to specific allergy triggers (allergens). Your immune system produces antibodies that detect the allergen and cause inflammatory reactions and the release of a chemical called histamine. Histamine causes hives,
hay fever
and other allergic symptoms.
The specific molecule in shellfish or fish that triggers allergy may be present in a range of foods, and you may then have an allergic reaction to all foods containing that molecule. Some people who are allergic to one type of fish may be allergic to another type of fish or they may have allergies to several crustaceans, such as prawn, crab and lobster. This is known as cross-reactivity. Speak to your clinical immunology/allergy specialist about cross-reactivity because it is difficult to predict.
The list of fish that can cause an allergic reaction is quite long and includes, but is not limited to:
barramundi
cod
flake
salmon
snapper
trout
tuna
whiting.
The list of shellfish (including molluscs and crustaceans) that can cause allergic reactions includes, but is not limited to:
calamari
crayfish
cuttlefish
lobster
mussels
oysters
prawns
squid.
The
Healthy Eating Advisory
Service
External Link
has more comprehensive lists of seafood that can cause an allergic reaction in some people. Visit your doctor for more information.
Diagnosis of shellfish and fish allergies
If you have allergic symptoms, visit your family doctor, who will ask some questions about your allergic reactions. You can also discuss your record of symptoms. To diagnose your allergy, your doctor may refer you to a specialist doctor known as a clinical immunology/allergy specialist.
Allergists can
test for allergies
using a number of methods depending on the type of potential allergy. To test for an allergy to shellfish or fish, the allergist may:
do a skin prick test
do a blood test
ask you to temporarily avoid all shellfish or fish (elimination diet), then follow up with the introduction of the food back into your diet (food challenge) under strict medical supervision.
Unproven methods to test for allergies
A number of methods claim to test for allergies, but they have not been
medically or scientifically
proven
External Link
. They can be costly and could lead to dangerous avoidance of certain foods. The Australasian Society of Clinical Immunology and Allergy (ASCIA) recommends that you do not use certain methods to have potential allergies tested. These methods include:
cytotoxic food testing
electrodermal testing
hair analysis
iridology
kinesiology
pulse testing
reflexology
Vega testing.
Always speak with your doctor if you are thinking of using a
complementary medicine
or
therapy
to test for allergies.
Treatment for shellfish and fish allergies
The only current treatment for food allergies is to avoid the food that causes your allergy. Even if you are careful, it is difficult to avoid all contact with a specific food.
If you are at risk of a severe allergic reaction and you have been prescribed an adrenaline injector (such as an EpiPen® or Anapen®), the Australasian Society of Clinical Immunology and Allergy (ASCIA) recommends that you have an
ASCIA Action Plan for
Anaphylaxis
External Link
specific to the brand of injector you have been prescribed.
If you are not at high risk, and have not been prescribed an adrenaline injector, ASCIA recommends that you have an
ASCIA Action Plan for Allergic
Reactions
External Link
.
To help with food avoidance, people with food allergies need to become familiar and comfortable with reading food labels. ASCIA has fact sheets to help you understand how to read food labels and what to avoid if you have a
shellfish
External Link
or
fish
External Link
allergy.
Inaccurate diagnosis can lead to expensive and ineffective treatments, and unnecessary food avoidance that can lead to malnutrition and food aversion, especially in children. Always speak to your doctor or a clinical immunology/allergy specialist about your food allergy diagnosis and treatment options.
Emergency treatment for severe allergic reactions
If you are at risk of a severe allergic reaction (anaphylaxis), carry an adrenaline injector such as an EpiPen® or Anapen®, your
ASCIA Action
Plan
External Link
and a means of calling for medical assistance, such as a mobile telephone.
Emergency responses for a severe allergic reaction are:
Lay the person flat – do not allow them to stand or walk.
Administer adrenaline with an injector (such as an EpiPen® or Anapen®).
Always dial triple zero (000) to call an ambulance in a medical emergency.
Further doses of adrenaline may be given if there is no response after 5 minutes.
Give adrenaline first, then asthma reliever puffer, if required.
If you are at risk of a severe allergic reaction, make sure you:
Have an ASCIA Action Plan for Anaphylaxis.
Carry an adrenaline injector (such as an EpiPen® or Anapen®) to treat a severe allergic reaction.
Consider wearing medical identification jewellery – this increases the likelihood that adrenaline will be administered in an emergency.
Avoid medication (where possible) that may increase the severity of allergic reaction or complicate its treatment – such as beta blockers.
Avoid the food to which you are allergic.
Tell food staff about your allergy when eating out.
Seek medical advice from a doctor or a clinical immunology/allergy specialist.
Where to get help
In an emergency, always call triple zero (000)
Emergency department of your nearest hospital
Your
GP (doctor)
NURSE-ON-CALL
Tel.
1300 60 60 24
– for health information and advice (24 hours, 7 days)
St John Ambulance
Australia
External Link
Tel.
1300 360 455
Australasian Society of Clinical Immunology and Allergy
(ASCIA)
External Link
Allergic and toxic reactions to
seafood
External Link
Locate a
specialist
External Link
Allergy and Anaphylaxis
Australia
External Link