Insect Bites/Urticaria Flashcards
What is the common clinical presentation of a spider bite?
Initial stinging, swelling, localized swelling, itching and inflammation
What are the severe reactions to spider bites and who are the culprits?
Black widow: pain within 30-60 minutes, then sweating, nausea, blurred vision, muscle cramps
Brown Recluse: redness, itching, pain within 6 hours; tissue necrosis if left untreated (cytotoxic)
What is the common clinical presentation of a tick bite?
Red papule at bite site, following may also occur: • Swelling • Blistering • Bruising • Itching
What is the severe reaction for a tick bite and who are the culprits?
Lyme disease: • 3-30 days after bite --> erythema migrans rash beginning at bite site and expanding gradually, flu-like symptoms: ○ Fever ○ Headache ○ Fatigue ○ Muscle and joint aches ○ Swollen lymph nodes • Days-months after bite --> severe headache, facial palsy, severe joint pain and swelling, heart palpitations, inflammation of the brain and spinal cord
Rocky Mountain Spotted Fever:
• 1-4 days after bite –> fever, headache, N/V, myalgia, maculopapular rash 2-4 days after onset of fever
• 5+ days –> altered mental status, coma, acute respiratory distress, necrosis, multiorgan system damage, petechial rash
What is the common clinical presentation of a mosquito bite?
Red, itchy papule develops within hours and subsides over a few days
What is the more severe reaction from a mosquito bite?
In patients who develop antibodies: large welts that last for several days
West Nile virus (2-15 days for appearance)
• Mild –> flu-like symptoms, possible rash
• Severe –> high fever, stiff neck, confusion, muscle weakness or degeneration
What is the common clinical presentation for a bee or vespid sting?
Pain, redness, swelling within 4-48 hours
What is the more severe reaction to a bee or vespid sting?
Extensive local reaction –> swelling over large area (whole limb) peaking at 48 hours and subsiding over 3-10 days
Systemic reaction –> headache, fever, N/V within 12-24 hours
Anaphylaxis –> trouble breathing or swallowing, swelling of lips or throat, rapid heart rate
What are the red flags warranting referral for an insect bite?
- Bullseye appearance around lesion
- Lesion is infected
- History of severe reaction
- Immunocompromised due to medication or conditions
- Lesion persisted >7 days or is not improving after 24h of treatment
Specifically for bee/vespid:
- Anaphylaxis
- Severe local reaction (>10cm diameter)
- Sting to tongue or mouth
- Multiple stings
What are the prevention measures for stings?
avoid areas with nests or hives, wear clothing that covers skin, limit time spent outdoors at dawn and dusk
Other:
• Cover drinks to avoid swallowing bees/wasps
• Eat indoors
• Avoid scented products
What are the prevention measures for tick and mosquito bites?
- avoid infested areas and standing by sources of water
- wear clothing that covers skin
- limit time spent outdoors at dusk and dawn
- consider mosquito netting (esp for <6mo)
Ticks: light coloured clothing (make ticks more visible), wear clothing tight at ankles and wrists, wear clothing with permethrin, inspect tick-prone areas and pets before going indoors
What are the types of insect repellent available, how do they work, how do you use them and at what strengths are they used?
Deet: offensive to insects; apply sparingly, may cause skin irritation, may be fatal if ingested, NOT recommended for children <6mo unless travelling to high risk areas
○ 6mo-12yr <10% QD
○ 2-12yr, <10% TID
○ >12yr, 30% TID
Icaridin/Picaridin: conceals human attractants
○ 10% q5h, QID
○ 20% q7h, BID
Soybean oil: conceals human attractants and cools skin temp
PMD: may conceal human attractants, not recommended for children <3y
○ Apply PRN up to BID
Citronella oil: offensive smell/taste to insects, may cause skin irritation, requires frequent application, not recommended for <2yrs
○ Apply PRN
Metofluthrin: released as vapour to repel insects, activate clip on device PRN, may cause skin/respiratory irritation, tremors and sympathetic activation possible if ingested
○ ~12h/disk
What types of insect repellent are safe in pregnant and breastfeeding women?
ALL of the list are safe in pregnancy and breastfeeding except citronella oil and metofluthrin (no safety data available)
What are the non-pharmacologic strategies available for the treatment of insect bites?
Stinger should be removed asap to decrease local reaction
• Ticks best removed using tweezers
○ Grasp tick close to head and avoid twisting or pulling too quickly
○ Using petrolatum, gasoline or matches are NOT RECOMMENDED (may damage skin further)
• Stingers can be removed gently scraping side to side with tweezers, finger nail or credit card
○ DON’T pull stingers (may force more venom into skin)
Clean the bite/sting with soap and warm water to decrease risk of secondary infection
Ice or cool compress may be applied to provide symptomatic relief and reduce swelling
• Home remedies like oatmeal, baking soda baths, toothpaste or salt and vinegar applied to the site may relieve symptoms but are not well studied
What are the pharmacologic options for treating insect bites and stings?
- OAH
- oral analgesics
- hydrocortisone 0.5-1%
- topicals containing local anesthetics, astringents, counter-irritants or ammonia/baking soda
- oral corticosteroids
- epinephrine (in cases of anaphylaxis)
Why and how are OAH used in the treatment of insect bites and stings?
reduce itching, swelling, and redness
• May be more effective than topical products which should be avoided due to risk of contact dermatitis
• 1st (diphenhydramine) and 2nd (cetirizine, desloratadine) generation are equally as effective but 2nd are better tolerated
• Cetirizine has an onset of 15-30 min but is more likely to cause sedation
Why and how is hydrocortsione used for the treatment of insect bites and stings?
Hydrocortisone 0.5-1%: applied QID for MAX 7 days to reduce itching, swelling and redness
• Can be prescribed by a pharmacist if covered or warranted for other reasons
• Studies on efficacy of TCS for insect bites and stings is limited
• Use cautiously on areas of broken skin
• Creams work best
Why and how are oral corticosteroids used in the treatment of insect bites and stings?
Oral Corticosteroids: may be needed for more severe local reactions
• Prednisone 1mg/kg (pharmacists cannot prescribe)
• Doxycycline -> post-exposure/prophylaxis/treatment of Lyme disease
When should the patient monitor and when does the pharmacist follow up on the treatment of insect bites and stings?
Patients or caregivers should monitor condition daily when self-management is appropriate, pharmacists should follow up in 24 hours
• If there is no improvement or worsening condition, refer
What is considered acute versus chronic urticaria?
Acute is <6 weeks
Chronic is >6 weeks
What is the common clinical presentation of urticaria?
• Appears as red or skin-coloured wheals
• Raised
• Well-circumscribed
• Often with central pallor
• Range in size (less than 1 cm to several cm)
• May coalesce as they enlarge
• Intensely pruritic
• May interfere with work or sleep
• May burn or sting
• May effect any part of the body but areas compressed by clothing or rub together may be affected more dramatically
• Generally last for 24 hours or less
• Can last from minutes to months or years
Do not bruise or scar unless there was skin trauma from scratching or they are associated with underlying disease
What are the red flags warranting referral of a patient presenting with urticaria?
Referral for further assessment needed:
• Angioedema
• Stridor, wheezing, or other indicators of respiratory disease
• S/S of systemic illness
• Lesions are hyperpigmented, bruised, blistered or ulcered
• Lesions have persisted for >48 hours
What are the goals of therapy for treating urticaria?
- Identification and removal of cause of skin reaction
- Providing symptomatic relief until spontaneous resolution occurs
- Ensuring appropriate care in case of more severe reaction
What are the non-pharmacological strategies for the treatment of acute and chronic urticaria? (6)
Avoidance of identified trigger
Wear loose fitting clothing
Take cool baths
• Use gentle, fragrance-free soaps and detergents
Applying cool compresses
Ensure proper skin protection
• Keep fingernails short to avoid scratching
AVOID alcohol and medications like acetylsalicylic acid and NSAIDS
When are pharmacological interventions indicated in the treatment of urticaria?
- trigger avoidance is not possible
- no trigger can be identified
- symptom relief is needed despite trigger avoidance
What is the first line pharmacological treatment in the management of acute urticaria?
1st Line –> 2nd generation H-1 Antihistamines: reduce wheal formation, pruritis and disruption of sleep
• Longer acting, relatively non-sedating
• 1st generation may be indicated in younger, healthy patients to help with sleep
• No strong evidence to suggest one agent is superior
• TAH not recommended because of contact dermatitis
• If they don’t work, an H-2 antihistamine like ranitidine may be added
○ Generally not required
○ Limited data to support
When are oral corticosteroids indicated in the management of acute urticaria?
when angioedema is present or symptoms have persisted for more than a few days
• Patient referral required
What are the first line pharmacological options for the treatment of chronic urticaria?
1st line –> H-1 antihistamines
• Dosed daily rather than PRN
• Some evidence says cetirizine may be modestly more effective than other agents for chronic hives
• If insufficient control in 2-4 weeks; dose can be titrated up to 4x usual dose
○ Increases risk of adverse effects
○ Not recommended in self-care
What is the step up in treatment from first line pharmacological options in the treatment of chronic urticaria?
Next steps:
• Omalizumab: can be added if there is not enough control in 2-4 weeks
• Cyclosporine: can be added onto OAH if there is not sufficient control within 6 months
○ Requires specialist supervision
What are the alternative pharmacological options for the treatment of chronic urticaria when needed for safety or cost reasons?
• H-2 receptor antihistamines can be added although not directly involved in itch
• Leukotriene receptor antagonist
○ Useful in patients with NSAID intolerance or cold urticaria
○ Pharmacists cannot prescribe for hives
• Doxepin
Pharmacists cannot prescribe, need to refer
If symptoms of chronic urticaria are severe, what else can be added to the treatment plan?
Short course corticosteroids may be added if symptoms are severe
• Potent topical corticosteroids may be beneficial for localized delayed-pressure urticaria
○ Pharmacists CAN prescribe for hives
