Hayfever and Allergies [completed] Flashcards
The number of hay fever sufferers is increasing by how much each year?
5%
What is an allergy?
The response of the immune system to a substance (allergen) that is usually harmless but the body reacts as if it’s harmful.
What is the immune response to allergens?
Production of antibodies
What is a serious, systemic, life threatening allergic reaction called?
Anaphylaxis
Outline what happens in an allergic reaction?
On first exposure the person forms IgE antibodies specific to the antigen
IgE attaches to high affinity Fc receptors on basophils and mast cells,
The immune system stores this in memory - SENSITISATION
The person may not have an allergic reaction one first contact but upon re-encountering the allergen it will bind to IgE causing cross linking between IgE and degranulation of mast cells.
The mast cells then release histamine - a chemical mediator
What are some common allergens?
Poison plants
Animal scratches
Pollen
Latex
Bee sting
Medication
Nuts and Shellfish
Dust
Mold and mildew
Animal dander
How often after exposure do allergic reactions occur?
within minutes
what is allergic rhinitis?
Inflammation of the nose - can cause runny, blocked nose and sneezing
What is allergic conjunctivitis?
Inflammation of the eyes -
IN BOTH EYES
watery, red and itchy eyes
What is urticaria?
Also known as hives or nettle rash, very itchy and red
What is angioedema?
Swelling of tissues - lips, tongue, throat and eyelids
Feels tingly at first
Can cause airway obstruction, difficulty talking or swallowing
Can be life threatening
What breathing difficulties may arise with allergic reactions?
Wheezing, chest tightness and breathlessness
Can be life threatening
How are mild allergies managed?
Person is offered advice and treatment
How are severe/unknown allergies managed?
Refer to a specialist for testing and advice on treatment?
What is the skin prick test?
A drop of liquid containing the allergen is placed on the skin as well as a drop of saline solution. The skin is then pricked with a lancet.
What would be a positive result in the skin prick test?
A raised bump (over 3mm diameter) after about 15 minutes that looks different to the control
What is intradermal testing for allergies?
A small amount of allergen is injected subcutaneously under skin to look for a reaction
What are patch tests for allergies?
The allergen is applied to a small disc placed onto the back and worn for two days.
What is allergy challenge testing
Increasing amounts of allergen given orally in order to establish if there is a reaction.
Especially good for food allergies BUT needs to be in a safe medical environment.
What is an example of a commercial allergy testing kit? why are they not recommended?
Hair analysis - has very little scientific evidence
What other tests may be carried out to diagnose an allergy?
Blood tests
What is a sensitivity?
An exaggeration of the normal effects of the substance.
Give an example of a sensitivity.
Drinking coffee –> caffeine causes palpitations and trembling
What is an intolerance?
When a substance causes unpleasant symptoms such as diarrhoea but DOES NOT involve the immune system. People with food intolerance can eat small amounts without issues
What are common symptoms of a food allergy
Itching, tingling, burning, swelling of mouth lips and throat
Vomiting
Urticaria – red raised rash
Swelling
How soon after eating does the allergic response begin?
immediately or within thirty minutes
What food commonly cause an allergic reaction?
Milk, eggs, nuts, peanuts, fish, shellfish and some fruits and vegetables
Can trace amount cause food allergy?
Yes depending on severity
What is the only way to prevent a reaction in a food allergy?
Complete avoidance
What are symptoms of a food intolerance?
Diarrhoea
Bloating
Stomach cramps
How soon after eating does a food intolerance occur?
After a few hours, caused by larger amounts of food (more food = stronger symptoms)
NOT LIFETHREATENING
Why does allergic rhinitis occur?
Nasal mucosa is exposed and sensitised to allergens to produce sneezing, nasal itching, discharge and congestion
What three things can allergic rhinitis be classified by:
Timing
Frequency
Persistence
What is perennial rhinitis?
Occurs through the entire year
What are some symptoms of perennial rhinitis?
Nose is congested
Reduced ability to smell (hyposmia)
Runny nose
Sneezing
Itchy nose
What are some common allergens that can cause perennial rhinitis?
house dust mites, animal dander, mould
How long should perennial rhinitis be treated for?
All year round and then 3-6 months after symptom control
What is seasonal rhinitis?
Occurs at the same time each year. Made worse when pollen count is higher.
What are the symptoms of seasonal rhinitis?
Blocked nose
Runny nose
sneezing
Itchy nose
Itchy red water eyes
Itchy throat
loss of smell
face pain
headache
wheezing
breathlessness
worsening/seasonal asthma
Who is hay fever more common in?
People with family members who have hay fever
People who have other allergies or asthma
When are the peak months for allergic rhinitis?
May - july
What is one of the most common allergens for perennial rhinitis and why?
House dust mite as present throughout the year
How can we distinguish between allergic and infective rhinitis
Discharge : watery in hay fever, mucopurulent in infections
Duration: hay fever can last months , infections 3-14 days
Symptoms: immediately on contact in hay fever but may take a few days in infections
Throat: itchy throat in hay fever sore throat in infections
Itchiness: itchy eyes and nose in hayfever, no itching in infections
Cough: cough more common in infection
What are some red flags in allergic rhinitis that may require referral?
Wheezing / Shortness of breath (may be asthma)
Tightness in chest
Associated ear pain - Abx?
Painful sinuses - Abx?
Purulent eye discharge
Severe symptoms unresponsive to therapy - short course of oral steroid ?
What are some symptoms of anaphylaxis?
Unconsciousness
Runny nose
Fast/slow heart rate
Itchy skin
Wheezing/cough
Swelling of lips, tongue or throat - difficulty speaking or swallowing
MAY GO INTO SHOCK - pale, clammy skin
What should you do if you suspect someone is having an anaphylactic reaction?
Diagnosis - issues in airway, breathing and circulation
Call - ambulance or resuscitation team and lie the patient flat with their feet elevated or sitting up to help with breathing. If pregnant lie on left side
Treatment - IM Adrenaline - if no improvement give adrenaline again every 5 minutes
Where is adrenaline ideally administered?
Intramsucularly into the middle of the patients thigh
Do you need a prescription to administer adrenaline in an emergency situation?
No
What formulations is adrenaline available as?
Ampoules or pre filled autoinjecter
What is the dose of adrenaline given to adults and children over 12 years?
500mcg
Anaphylaxis is medical emergency and 999 has to be called. What will happen to the patient the hospital?
They are given antihistamines, steroids or further testig
Observed for 6-12 hours depending on their response to treatment
May be referred to a specialist allergy service on discharge and given adrenaline injection pens
What else may a patient have to keep on them if they are at risk of anaphylaxis?
Medical alert bracelet or card
How can a patient manage an allergy?
Avoiding allergens
Taking medication or using it to treat an allergic reaction
Desensitisation (immunotherapy)
When is desensitisation used to manage allergies?
In severe cases to wasp stings, bee stings, severe hay fever and some animal allergies BUT NOT IN MULTIPLE ALLERGIES
What happens during allergy desensitisation?
Allergen given via injection
Tiny amount so allergic reaction not triggered but can teach the immune system not to produce a lot of IgE
Dose is increase at a regular interval (weeks- months)
DONE IN A SPECIALIST HOSPITAL OUTPATIENT SETTING
What are some disadvantages to desensitisation immunotherapy?
Time consuming
Expensive
Risky
used as a last resort BUT TREATS DISEASE CAUSE
What is the first line treatment for mild-moderate allergy symptoms?
Antihistamines
How do antihistamines work?
Compete with histamine for receptor blocking the actions of histamine so allergic response is prevented or reduced
Which allergy symptom is an antihistamine not as effective on?
nasal congestion
After how long will there be relief of symptoms after using oral and topical antihistamines?
Oral - 1 hour
Topical - 15 minutes
What are the two types of antihistamines?
1st generation sedating
2nd generation non-sedating
What types of antihistamines are reccomended by NICE?
Intranasal or a second generation non sedating antihistamine taken orally
What are some oral sedating antihistamines?
Chlorphenamine (Puritan)
Promethazine (Phenergen)
Diphenhydramine (Nytol)
Which oral sedating antihistamine is not actually indicated for allergic conditions?
Diphenhydramine
Why do first generation antihistamines cause drowsiness?
Cross the BBB and bind to H1 receptors in the brain
What is the usual frequency of Piriton (chlorphenamine) in adults)
Every 4-6 hours?
Who might sedating antihistamines not be appropriate for?
Elderly - risk of falls and confusion
What advice should be given to people taking sedating antihistamines?
Do not drive or operate heavy machinery
Avoid alcohol as this can enhance the sedating effect
What are some non-sedating antihistamines
Loratadine (Claritin)
Cetirizine (Piriteze)
Acrivastine (Benadryl)
Fexofenadine (Allevia)
How often are non sedating antihistamines taken?
1 tablet once a day or THREE TIMES A DAY FOR ACRIVASTINE
Fexofenadine used to be POM only. What strength is still POM and which one is available as a P medicine?
180mg - POM
120mg - P
Why do non sedating antihistamines have less effect on the brain?
Less penetration of blood brain barrier
What are some topical antihistamines?
Azelastine eye drops (POM - 4 years and over)
Azelastine nasal spray (Rhinolast - POM only)
Antazoline + Xylometazoline eye drops (P - 12 years and over)
How do antazoline and xylometazoline eye drops work?
antihistamine AND vasoconstrictor
reduces eye redness and itching
May cause temporary local irritation
What are some mast cell stabilisers?
Sodium cromoglicate eyedrops (P - 6 years and above)
Lodoxamide eye drops (P - 4 years and above)
Olopatadine drops (POM - 3 years and above)
How often do sodium cromoglicate eye drops need to be used?
4 times a day
How doe mast cell stabilisers work?
Stabilise mast cells preventing degranulation and the release of inflammatory mediators such as histamine.
When is it ideal to administer mast cell stabilisers?
BEFORE allergen exposure
What can happen of the first administration of a mast cell stabiliser?
Stinging sensation
How soon after opening should mast cell stabiliser eye drops be discarded
4 weeks
What are some examples of nasal corticosteroids?
Beclomethasone (beconase)
Fluticasone (Pirinase)
Budesonide (benacort)
Mometasone (Clarinaze0
What is the usual dose frequency for nasal corticosteroids?
Varies from once daily to twice daily
Can nasal corticosteroids cause systemic effects?
Unlikely but patient should still be aware
True or false. Nasal corticosteroids are first line for SEVERE symptoms.
TRUE
What symptoms are nasal corticosteroids good for?
Nasal congestion
Rhinorrhoea (runny nose)
itching
sneezing
Also eases eye symptoms
How long does it take to see the maximum effect of nasal corticosteroids?
2-3 weeks
What age group are nasal corticosteroids licensed for OTC supply?
18 years and above
What is the ideal way to use nasal corticosteroids in a pollen allergy?
Use 1 or 2 weeks before exposure to delay onset of symptoms
What are some examples of of nasal decongestants?
Xylometazoline (Otrivine)
What is the maximum duration of use of nasal decongestant sprays and drops?
5-7 days
Why should nasal decongestants only be used short term
They can cause rebound congestion which can be worser than before
Why is it helpful to use a decongestant just before starting a nasal corticosteroid?
Congestion can stop the corticosteroid reaching the mucosa making it less effective
What are some examples of oral decongestants?
Pseudoephedrine, ephedrine, phenylephrine
What are some uses for oral decongestants?
Allergic Rhinitis
Common cold
Flu
What are the limits for supply of OTC ephedrine and pseudoephedrine?
Pseudoephedrine 720mg
Ephedrine 180mg
They are prone to abuse.
What comorbidities should we not supply oral decongestants in?
Diabetes
High blood pressure
Chronic heart failure
What age group are oral decongestants licensed for OTC sale in?
12 years and over
What is the duration of action for oral decongestants?
6 hours
What are some self-management tips to help with hay fever
- Nasal irrigation
- Avoid grassy areas especially when mowed or high pollen count
- Avoid drying washing outside when pollen count is high
- Keep window shut
- Vacuum regularly and use damp duster
- Do not smoke
What are some self-management tips to help allergies?
Animal allergy
- ideally do not allow animal in house :(
- wash animal and surface they may regularly come into contact with
Occupational allergies
- reduce exposure e.g. by wearing latex free gloves or a dust mask
- adequate ventilation
- avoid hazardous chemicals where possible
House dust mite allergy
- use synthetic pillows and acrylic duvets
- wash bedding and fluffy toys at least once a week on hot cycle
- wooden or hard floors instead of carpet
