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Tick Exposure and Tick Borne Illness ConcernAPPROACH

INFECTIOUS DISEASE AND FEVER SYNDROMES · 19 SECTIONS

⚲

548 items

☷ Legend

⚲

Resuscitation and Universal Approaches9▾

Chest and Cardiovascular12▾

Respiratory11▾

Abdominal and Gastrointestinal24▾

Renal and Urinary7▾

Neurologic11▾

Back and Neck8▾

Women's Health, Pregnancy, and GU11▾

Infectious Disease and Fever Syndromes11▾

Fever In The Immunocompromised Patient Fever With Rash Animal Bites And Rabies Risk Assessment Tick Exposure And Tick Borne Illness Concern Sepsis Concern Without Clear Source Soft Tissue Infection Concern Abscess And Skin Infection Concern Sore Throat Sore Throat And Pharyngitis Symptoms Meningitis Envenomation And Bites

Allergy and Dermatology7▾

Musculoskeletal and Extremities14▾

Trauma and Wounds14▾

ENT, Eye, Dental10▾

Endocrine, Metabolic, and Abnormal Labs9▾

Toxicology and Behavioral14▾

Pediatrics16▾

Environmental and Exposure4▾

01History/hx80

Presenting concern

›Presentation overview

›Tick bite

›Concern for tick borne illness

›Local symptoms

›Systemic symptoms

Exposure details

›Tick exposure characterization

›Date and time of tick discovery

›Estimated attachment duration

›Tick appearance

›Flat

›Engorged

›Tick removal method

›Tick retained for identification

›Geographic location of exposure

›Endemic area for Ixodes

›Travel outside region

›Outdoor activities

›Hiking

›Camping

›Yard work

›Animal exposure

›Dogs

›Deer

Symptoms OPQRST

›Symptom characterization

›Onset

02Alarm Features/alarm28

Immediate escalation triggers

›Resuscitation triggers

›Hypotension

›Altered mental status

›Respiratory distress

›Seizure

›Anaphylaxis

›Rapidly progressive rash

›Purpura

›Petechiae

Vital sign danger thresholds

›High risk vitals

›Temperature 39.5 C or higher with toxicity

›Systolic blood pressure under 90 mmHg

›Heart rate 130 or higher

›Respiratory rate 30 or higher

›Oxygen saturation under 92 percent on room air

High risk syndromes

›Cannot miss presentations

›Suspected Rocky Mountain spotted fever

›Suspected meningitis or encephalitis

›Suspected myocarditis

›High degree atrioventricular block

›Progressive ascending weakness

›Tick paralysis concern

›Severe hemolysis concern

›Babesiosis risk with anemia or jaundice

03Medications/meds17

Current and recent medications

›Medication reconciliation

›Antibiotics in last 30 days

›Antipyretics

›NSAIDs

›Acetaminophen

›Immunosuppressants

›Corticosteroids

›Biologics

›Anticoagulants

Allergies and contraindications

›Antibiotic safety screen

›Tetracycline allergy

›Prior severe cutaneous adverse reaction

›Pregnancy or lactation considerations for doxycycline

High risk interactions

›Doxycycline interaction screen

›Warfarin interaction risk

›Retinoids

›Antacids and iron reducing absorption

04Diet/diet10

Intake and hydration

›Recent intake pattern

›Poor oral intake

›Vomiting limiting intake

›Diarrhea limiting intake

›Dehydration risk

Exposures relevant to symptoms

›Exposure pattern

›Alcohol intake

›Caffeine intake

›Recent raw milk

›Recent undercooked meat

05Review of Systems/ros33

Constitutional and infectious

›Constitutional review

›Fever

›Chills

›Night sweats

›Weight loss

Skin and mucous membranes

›Skin review

›Expanding rash

›Pruritus

›Petechiae

›Eschar

Neurologic

›Neurologic review

›Headache

›Neck stiffness

›Photophobia

›Facial palsy

›Radicular pain

›Weakness

›Paresthesia

›Gait change

Cardiorespiratory

›Cardiorespiratory review

›Chest pain

›Palpitations

›Dyspnea

›Syncope

06Collateral History and Family History/chafh12

Collateral sources

›Additional history sources

›Family witness of tick removal

›Photo of tick

›Photo of rash

Family history

›Family risk factors

›Immunodeficiency

›Hemolytic anemia

›Asplenia history

Household and community exposures

›Shared exposures

›Household members with tick bites

›Pets with ticks

›Local tick reports

07Risk Factors/rf20

Exposure and geography

›Epidemiologic risk

›Ixodes habitat exposure

›Endemic region for Lyme disease

›Peak season exposure

Host risk factors for severe disease

›Severe disease risk factors

›Age 65 or older

›Asplenia

›Immunosuppression

›Chronic liver disease

›Pregnancy

Specific disease risk anchors

›Disease specific risk factors

›Babesiosis risk

›Asplenia

›Immunosuppression

›Anaplasmosis risk

›Ixodes exposure

›Leukopenia or thrombocytopenia presentation

›RMSF risk

›Febrile illness with rash

›Delayed doxycycline risk

08Differential Diagnosis/ddx66

Life threatening

›Life threatening causes

›Rocky Mountain spotted fever

›Fever with headache

›Rash

›Thrombocytopenia

›Hyponatremia

›Ehrlichiosis

›Fever

›Leukopenia

›Thrombocytopenia

›Elevated transaminases

›Anaplasmosis

›Fever

›Cytopenias

›Elevated transaminases

›Babesiosis

›Hemolytic anemia

›Jaundice

›Dark urine

›Meningitis or encephalitis

›Neck stiffness

›Altered mental status

›Lyme carditis

›Syncope

›Palpitations

›Atrioventricular block

›Sepsis of alternate source

09Past Medical History/pmh14

Comorbidities

›Relevant chronic conditions

›Asplenia

›Immunosuppression

›HIV

›Chronic kidney disease

›Chronic liver disease

›Cardiac conduction disease

Surgical and device history

›Procedures and devices

›Pacemaker

›Prosthetic joints

›Valve replacement

Baseline function

›Baseline status

›Baseline mobility

›Baseline neurologic deficits

10Physical Exam/exam36

Vitals and general

›Initial assessment

›Temperature trend

›Hemodynamic stability

›Toxic appearance

Skin exam

›Skin and bite site

›Tick parts retained

›Local reaction size

›Expanding rash size progression

›Erythema migrans morphology

›Central clearing

›Multiple lesions

›Petechiae

›Purpura

›Eschar

Head and neck

›Head and neck

›Conjunctival injection

›Meningeal signs

›Lymphadenopathy

Cardiopulmonary

›Cardiac and lung exam

›Bradycardia

›New murmur

›Signs of heart failure

›Pulmonary crackles

11Lab Studies/labs35

Core ED labs when systemic illness

›Baseline laboratory evaluation

›CBC with differential

›CMP

›AST

›ALT

›Bilirubin

›Creatinine

›Sodium

›CRP

Tick borne targeted testing

›Disease specific testing

›Lyme serology

›Two tier testing when compatible syndrome

›Early localized erythema migrans diagnosis is clinical

›Early serology may be negative

›Anaplasma testing

›PCR early illness

›Peripheral smear morulae low sensitivity

›Ehrlichia testing

›PCR early illness

›Serology paired samples when needed

›Babesia testing

›Peripheral smear

›PCR if smear negative with high suspicion

Sepsis and complications

›Severity evaluation

›Blood cultures if febrile and toxic

12Imaging/img25

Scoring Systems

›Decision tools and criteria

›High risk Ixodes bite criteria for Lyme prophylaxis

›Ixodes species likely

›Endemic region exposure

›Attachment 36 hours or longer

›Prophylaxis within 72 hours of removal

›Doxycycline safe for patient

›SILC score for high degree atrioventricular block

›Low probability 0 to 2

›Intermediate probability 3 to 6

›High probability 7 to 12

MRI

›MRI indications

›Suspected encephalitis with focal deficits

›Suspected myelitis or radiculopathy

›Consider lumbar spine MRI for severe radicular pain with neuro deficits

›CT indications

›CT head if altered mental status with concern for intracranial process

›CT chest if alternate source and respiratory distress

›Contrast risk screening

›Kidney injury

›Prior contrast reaction

Ultrasound

›Ultrasound use cases

›Joint effusion assessment

›Soft tissue abscess evaluation at bite site

13Special Tests/spec23

Tick and rash evaluation

›Bedside and practical tests

›Tick identification support

›Photo documentation

›Local public health tick ID options

›Erythema migrans clinical diagnosis

›Expanding rash over days

›Size typically greater than 5 cm

Neurologic and CSF evaluation

›Lumbar puncture considerations

›Suspected meningitis or encephalitis

›Opening pressure when indicated

›CSF studies

›Cell count and differential

›Protein

›Glucose

›CSF PCR per syndrome and local protocol dependent

Joint and hematology procedures

›Procedural diagnostics

›Arthrocentesis for hot swollen joint

›Cell count

›Crystal analysis

›Gram stain and culture

›Peripheral smear for babesiosis

›Parasitemia estimate

›Repeat smear if high suspicion

14ECG/ecg21

Indications and key findings

›ECG use in tick borne illness

›Cardiac symptoms

›Palpitations

›Chest pain

›Dyspnea

›Syncope

›Bradycardia

›Known or suspected Lyme disease with systemic symptoms

Lyme carditis patterns

›Conduction abnormalities

›PR prolongation

›First degree atrioventricular block

›Second degree atrioventricular block

›Third degree atrioventricular block

ECG escalation thresholds

›High risk ECG thresholds

›PR interval 300 ms or longer

›Second degree atrioventricular block

›Third degree atrioventricular block

›Ventricular escape rhythm

Serial ECG logic

›Monitoring strategy

›Repeat ECG with symptom change

›Continuous monitoring when high grade block or PR 300 ms or longer

15Assessment/ax27

Problem representation

›Clinical synthesis

›Tick exposure with symptoms compatible with tick borne illness

›Time since exposure

›Region risk level

Working diagnoses

›Working diagnosis set

›Tick bite with no symptoms

›Lyme prophylaxis eligibility determination

›Observation pathway if not eligible

›Early localized Lyme disease erythema migrans (A69.2)

›Clinical diagnosis when typical

›Serology may be negative early

›Suspected rickettsial disease

›RMSF concern if fever with headache and rash

›Empiric doxycycline threshold low

›Suspected anaplasmosis or ehrlichiosis

›Cytopenias

›Elevated transaminases

›Suspected babesiosis

›Hemolysis features

›Asplenia risk

Severity and risk stratification

›Risk stratification

›Toxic appearance or organ dysfunction

›Neurologic involvement

›Cardiac involvement

›Hemolysis severity

16Plan/plan51

First 5 minutes for the critical patient

›Immediate stabilization

›Cardiac monitoring when unstable or conduction concern

›Two large bore IV if sepsis concern

›Oxygen for hypoxemia

›Point of care glucose if altered mental status

›Early antibiotics for suspected rickettsial disease

Differential Management

›!Tick-borne illness (Lyme disease)→›!Rocky Mountain Spotted Fever→›Ehrlichiosis→

Diagnostic sequencing

›Testing plan

›CBC and CMP when systemic symptoms

›ECG when cardiac symptoms or bradycardia

›Targeted tick borne testing based on syndrome

›Lumbar puncture when meningitis or encephalitis concern

Empiric and directed therapy

›Antibiotic strategy

›Lyme post exposure prophylaxis when high risk bite

›Doxycycline 200 mg orally once

›Children doxycycline 4.4 mg per kg orally once

›Maximum 200 mg once

›Within 72 hours of tick removal

›Not for low risk bites

›Suspected RMSF

›Doxycycline 100 mg orally or IV every 12 hours

›Children doxycycline 2.2 mg per kg every 12 hours

17Disposition/dispo23

Admission and ICU criteria

›Higher level of care indications

›Shock or persistent hypotension after fluids

›Altered mental status

›Meningitis or encephalitis concern

›PR interval 300 ms or longer

›Second or third degree atrioventricular block

›Significant anemia or hemolysis

›Parasitemia concern in babesiosis

›Inability to tolerate oral therapy

Observation pathway

›Observation suitable scenarios

›Moderate systemic symptoms without organ dysfunction

›Pending key labs with stable vitals

›Mild conduction abnormalities with reliable follow up

Discharge criteria

›Discharge requirements

›Hemodynamic stability

›No alarm features

›Able to tolerate oral intake

›Reliable follow up within 24 to 72 hours when indicated

›Clear return precautions

Follow up timing

›Follow up plan

›Primary care within 1 week

›Infectious diseases within 1 to 2 weeks if confirmed Lyme complications

›Cardiology within 24 to 72 hours for mild Lyme carditis local protocol dependent

18Discharge Instructions/di18

Copy discharge instructions

›Patient instructions

›You were seen after a tick bite or possible tick borne illness

›Watch for symptoms for 30 days after a tick bite

›Fever

›New rash that expands over days

›Severe headache

›Neck stiffness

›New weakness or facial droop

›Palpitations

›Chest pain

›Fainting

›New joint swelling

›Dark urine or yellow skin

›Return to the emergency department right away if any of the above occur

›If you were given antibiotics, take them exactly as prescribed

›Avoid excess sun exposure while taking doxycycline

›Seek care if vomiting prevents keeping medication down

›Follow up with your clinician within the recommended time window

19References/r9

Guidelines and key sources

›Reference list

›Infectious Diseases Society of America IDSA AAN ACR Lyme disease guideline 2020

›CDC Lyme disease post exposure prophylaxis handout

›CDC Lyme treatment and post exposure antibiotics page 2024

›Public Health Ontario Lyme disease antibiotic prophylaxis algorithm 2023

›Canada Public Health Lyme disease prevention and transmission page 2024

›CDC Rocky Mountain spotted fever clinical care page 2025

›CDC Lyme carditis clinical care page 2024

›Suspicious Index in Lyme Carditis score derivation Besant 2018

Evidence & Review

Reviewed by SymptomDx Medical Team · Last reviewed February 24, 2026

SymptomDx is an educational tool for medical professionals. It does not replace clinical judgment. Verify all clinical data and drug dosages with authoritative sources.

Tick Exposure and Tick Borne Illness ConcernAPPROACH

INFECTIOUS DISEASE AND FEVER SYNDROMES · 19 SECTIONS

⚲

548 items

☷ Legend

⚲

Resuscitation and Universal Approaches9▾

Chest and Cardiovascular12▾

Respiratory11▾

Abdominal and Gastrointestinal24▾

Renal and Urinary7▾

Neurologic11▾

Back and Neck8▾

Women's Health, Pregnancy, and GU11▾

Infectious Disease and Fever Syndromes11▾

Allergy and Dermatology7▾

Musculoskeletal and Extremities14▾

Trauma and Wounds14▾

ENT, Eye, Dental10▾

Endocrine, Metabolic, and Abnormal Labs9▾

Toxicology and Behavioral14▾

Pediatrics16▾

Environmental and Exposure4▾

01History/hx80

Presenting concern

›Presentation overview

›Tick bite

›Concern for tick borne illness

›Local symptoms

›Systemic symptoms

Exposure details

›Tick exposure characterization

›Date and time of tick discovery

›Estimated attachment duration

›Tick appearance

›Flat

›Engorged

›Tick removal method

›Tick retained for identification

›Geographic location of exposure

›Endemic area for Ixodes

›Travel outside region

›Outdoor activities

›Hiking

›Camping

›Yard work

›Animal exposure

›Dogs

›Deer

Symptoms OPQRST

›Symptom characterization

›Onset

02Alarm Features/alarm28

Immediate escalation triggers

›Resuscitation triggers

›Hypotension

›Altered mental status

›Respiratory distress

›Seizure

›Anaphylaxis

›Rapidly progressive rash

›Purpura

›Petechiae

Vital sign danger thresholds

›High risk vitals

›Temperature 39.5 C or higher with toxicity

›Systolic blood pressure under 90 mmHg

›Heart rate 130 or higher

›Respiratory rate 30 or higher

›Oxygen saturation under 92 percent on room air

High risk syndromes

›Cannot miss presentations

›Suspected Rocky Mountain spotted fever

›Suspected meningitis or encephalitis

›Suspected myocarditis

›High degree atrioventricular block

›Progressive ascending weakness

›Tick paralysis concern

›Severe hemolysis concern

›Babesiosis risk with anemia or jaundice

03Medications/meds17

Current and recent medications

›Medication reconciliation

›Antibiotics in last 30 days

›Antipyretics

›NSAIDs

›Acetaminophen

›Immunosuppressants

›Corticosteroids

›Biologics

›Anticoagulants

Allergies and contraindications

›Antibiotic safety screen

›Tetracycline allergy

›Prior severe cutaneous adverse reaction

›Pregnancy or lactation considerations for doxycycline

High risk interactions

›Doxycycline interaction screen

›Warfarin interaction risk

›Retinoids

›Antacids and iron reducing absorption

04Diet/diet10

Intake and hydration

›Recent intake pattern

›Poor oral intake

›Vomiting limiting intake

›Diarrhea limiting intake

›Dehydration risk

Exposures relevant to symptoms

›Exposure pattern

›Alcohol intake

›Caffeine intake

›Recent raw milk

›Recent undercooked meat

05Review of Systems/ros33

Constitutional and infectious

›Constitutional review

›Fever

›Chills

›Night sweats

›Weight loss

Skin and mucous membranes

›Skin review

›Expanding rash

›Pruritus

›Petechiae

›Eschar

Neurologic

›Neurologic review

›Headache

›Neck stiffness

›Photophobia

›Facial palsy

›Radicular pain

›Weakness

›Paresthesia

›Gait change

Cardiorespiratory

›Cardiorespiratory review

›Chest pain

›Palpitations

›Dyspnea

›Syncope

06Collateral History and Family History/chafh12

Collateral sources

›Additional history sources

›Family witness of tick removal

›Photo of tick

›Photo of rash

Family history

›Family risk factors

›Immunodeficiency

›Hemolytic anemia

›Asplenia history

Household and community exposures

›Shared exposures

›Household members with tick bites

›Pets with ticks

›Local tick reports

07Risk Factors/rf20

Exposure and geography

›Epidemiologic risk

›Ixodes habitat exposure

›Endemic region for Lyme disease

›Peak season exposure

Host risk factors for severe disease

›Severe disease risk factors

›Age 65 or older

›Asplenia

›Immunosuppression

›Chronic liver disease

›Pregnancy

Specific disease risk anchors

›Disease specific risk factors

›Babesiosis risk

›Asplenia

›Immunosuppression

›Anaplasmosis risk

›Ixodes exposure

›Leukopenia or thrombocytopenia presentation

›RMSF risk

›Febrile illness with rash

›Delayed doxycycline risk

08Differential Diagnosis/ddx66

Life threatening

›Life threatening causes

›Rocky Mountain spotted fever

›Fever with headache

›Rash

›Thrombocytopenia

›Hyponatremia

›Ehrlichiosis

›Fever

›Leukopenia

›Thrombocytopenia

›Elevated transaminases

›Anaplasmosis

›Fever

›Cytopenias

›Elevated transaminases

›Babesiosis

›Hemolytic anemia

›Jaundice

›Dark urine

›Meningitis or encephalitis

›Neck stiffness

›Altered mental status

›Lyme carditis

›Syncope

›Palpitations

›Atrioventricular block

›Sepsis of alternate source

09Past Medical History/pmh14

Comorbidities

›Relevant chronic conditions

›Asplenia

›Immunosuppression

›HIV

›Chronic kidney disease

›Chronic liver disease

›Cardiac conduction disease

Surgical and device history

›Procedures and devices

›Pacemaker

›Prosthetic joints

›Valve replacement

Baseline function

›Baseline status

›Baseline mobility

›Baseline neurologic deficits

10Physical Exam/exam36

Vitals and general

›Initial assessment

›Temperature trend

›Hemodynamic stability

›Toxic appearance

Skin exam

›Skin and bite site

›Tick parts retained

›Local reaction size

›Expanding rash size progression

›Erythema migrans morphology

›Central clearing

›Multiple lesions

›Petechiae

›Purpura

›Eschar

Head and neck

›Head and neck

›Conjunctival injection

›Meningeal signs

›Lymphadenopathy

Cardiopulmonary

›Cardiac and lung exam

›Bradycardia

›New murmur

›Signs of heart failure

›Pulmonary crackles

11Lab Studies/labs35

Core ED labs when systemic illness

›Baseline laboratory evaluation

›CBC with differential

›CMP

›AST

›ALT

›Bilirubin

›Creatinine

›Sodium

›CRP

Tick borne targeted testing

›Disease specific testing

›Lyme serology

›Two tier testing when compatible syndrome

›Early localized erythema migrans diagnosis is clinical

›Early serology may be negative

›Anaplasma testing

›PCR early illness

›Peripheral smear morulae low sensitivity

›Ehrlichia testing

›PCR early illness

›Serology paired samples when needed

›Babesia testing

›Peripheral smear

›PCR if smear negative with high suspicion

Sepsis and complications

›Severity evaluation

›Blood cultures if febrile and toxic

12Imaging/img25

Scoring Systems

›Decision tools and criteria

›High risk Ixodes bite criteria for Lyme prophylaxis

›Ixodes species likely

›Endemic region exposure

›Attachment 36 hours or longer

›Prophylaxis within 72 hours of removal

›Doxycycline safe for patient

›SILC score for high degree atrioventricular block

›Low probability 0 to 2

›Intermediate probability 3 to 6

›High probability 7 to 12

MRI

›MRI indications

›Suspected encephalitis with focal deficits

›Suspected myelitis or radiculopathy

›Consider lumbar spine MRI for severe radicular pain with neuro deficits

›CT indications

›CT head if altered mental status with concern for intracranial process

›CT chest if alternate source and respiratory distress

›Contrast risk screening

›Kidney injury

›Prior contrast reaction

Ultrasound

›Ultrasound use cases

›Joint effusion assessment

›Soft tissue abscess evaluation at bite site

13Special Tests/spec23

Tick and rash evaluation

›Bedside and practical tests

›Tick identification support

›Photo documentation

›Local public health tick ID options

›Erythema migrans clinical diagnosis

›Expanding rash over days

›Size typically greater than 5 cm

Neurologic and CSF evaluation

›Lumbar puncture considerations

›Suspected meningitis or encephalitis

›Opening pressure when indicated

›CSF studies

›Cell count and differential

›Protein

›Glucose

›CSF PCR per syndrome and local protocol dependent

Joint and hematology procedures

›Procedural diagnostics

›Arthrocentesis for hot swollen joint

›Cell count

›Crystal analysis

›Gram stain and culture

›Peripheral smear for babesiosis

›Parasitemia estimate

›Repeat smear if high suspicion

14ECG/ecg21

Indications and key findings

›ECG use in tick borne illness

›Cardiac symptoms

›Palpitations

›Chest pain

›Dyspnea

›Syncope

›Bradycardia

›Known or suspected Lyme disease with systemic symptoms

Lyme carditis patterns

›Conduction abnormalities

›PR prolongation

›First degree atrioventricular block

›Second degree atrioventricular block

›Third degree atrioventricular block

ECG escalation thresholds

›High risk ECG thresholds

›PR interval 300 ms or longer

›Second degree atrioventricular block

›Third degree atrioventricular block

›Ventricular escape rhythm

Serial ECG logic

›Monitoring strategy

›Repeat ECG with symptom change

›Continuous monitoring when high grade block or PR 300 ms or longer

15Assessment/ax27

Problem representation

›Clinical synthesis

›Tick exposure with symptoms compatible with tick borne illness

›Time since exposure

›Region risk level

Working diagnoses

›Working diagnosis set

›Tick bite with no symptoms

›Lyme prophylaxis eligibility determination

›Observation pathway if not eligible

›Early localized Lyme disease erythema migrans (A69.2)

›Clinical diagnosis when typical

›Serology may be negative early

›Suspected rickettsial disease

›RMSF concern if fever with headache and rash

›Empiric doxycycline threshold low

›Suspected anaplasmosis or ehrlichiosis

›Cytopenias

›Elevated transaminases

›Suspected babesiosis

›Hemolysis features

›Asplenia risk

Severity and risk stratification

›Risk stratification

›Toxic appearance or organ dysfunction

›Neurologic involvement

›Cardiac involvement

›Hemolysis severity

16Plan/plan51

First 5 minutes for the critical patient

›Immediate stabilization

›Cardiac monitoring when unstable or conduction concern

›Two large bore IV if sepsis concern

›Oxygen for hypoxemia

›Point of care glucose if altered mental status

›Early antibiotics for suspected rickettsial disease

Differential Management

›!Tick-borne illness (Lyme disease)→›!Rocky Mountain Spotted Fever→›Ehrlichiosis→

Diagnostic sequencing

›Testing plan

›CBC and CMP when systemic symptoms

›ECG when cardiac symptoms or bradycardia

›Targeted tick borne testing based on syndrome

›Lumbar puncture when meningitis or encephalitis concern

Empiric and directed therapy

›Antibiotic strategy

›Lyme post exposure prophylaxis when high risk bite

›Doxycycline 200 mg orally once

›Children doxycycline 4.4 mg per kg orally once

›Maximum 200 mg once

›Within 72 hours of tick removal

›Not for low risk bites

›Suspected RMSF

›Doxycycline 100 mg orally or IV every 12 hours

›Children doxycycline 2.2 mg per kg every 12 hours

17Disposition/dispo23

Admission and ICU criteria

›Higher level of care indications

›Shock or persistent hypotension after fluids

›Altered mental status

›Meningitis or encephalitis concern

›PR interval 300 ms or longer

›Second or third degree atrioventricular block

›Significant anemia or hemolysis

›Parasitemia concern in babesiosis

›Inability to tolerate oral therapy

Observation pathway

›Observation suitable scenarios

›Moderate systemic symptoms without organ dysfunction

›Pending key labs with stable vitals

›Mild conduction abnormalities with reliable follow up

Discharge criteria

›Discharge requirements

›Hemodynamic stability

›No alarm features

›Able to tolerate oral intake

›Reliable follow up within 24 to 72 hours when indicated

›Clear return precautions

Follow up timing

›Follow up plan

›Primary care within 1 week

›Infectious diseases within 1 to 2 weeks if confirmed Lyme complications

›Cardiology within 24 to 72 hours for mild Lyme carditis local protocol dependent

18Discharge Instructions/di18

Copy discharge instructions

›Patient instructions

›You were seen after a tick bite or possible tick borne illness

›Watch for symptoms for 30 days after a tick bite

›Fever

›New rash that expands over days

›Severe headache

›Neck stiffness

›New weakness or facial droop

›Palpitations

›Chest pain

›Fainting

›New joint swelling

›Dark urine or yellow skin

›Return to the emergency department right away if any of the above occur

›If you were given antibiotics, take them exactly as prescribed

›Avoid excess sun exposure while taking doxycycline

›Seek care if vomiting prevents keeping medication down

›Follow up with your clinician within the recommended time window

19References/r9

Guidelines and key sources

›Reference list

›Infectious Diseases Society of America IDSA AAN ACR Lyme disease guideline 2020

›CDC Lyme disease post exposure prophylaxis handout

›CDC Lyme treatment and post exposure antibiotics page 2024

›Public Health Ontario Lyme disease antibiotic prophylaxis algorithm 2023

›Canada Public Health Lyme disease prevention and transmission page 2024

›CDC Rocky Mountain spotted fever clinical care page 2025

›CDC Lyme carditis clinical care page 2024

›Suspicious Index in Lyme Carditis score derivation Besant 2018

Evidence & Review

Reviewed by SymptomDx Medical Team · Last reviewed February 24, 2026

SymptomDx is an educational tool for medical professionals. It does not replace clinical judgment. Verify all clinical data and drug dosages with authoritative sources.