Should Your Child See a Doctor?

Infection Exposure Questions – Contagiousness


  • This topic includes information about the transmission of common infections, including how long to stay out of school or daycare
  • Incubation Period: Time interval between exposure to the infection and onset of symptoms.
  • Contagious Period: Time interval during which a sick child's disease is contagious to others. With precautions, children sometimes can return to day care and school before this period is over.
  • Infections that are not Contagious: Many common bacterial infections are not contagious (e.g., ear infections, sinus infections, bladder infections, kidney infections, and pneumonia). Sexually transmitted diseases are not contagious to children unless there is sexual contact or shared bathing.

Infection Exposure Table

Skin Infections/Rashes:  
Chickenpox 10-21 2 days before rash until all sores have crusts (6 - 7days)
Fifth disease (Erythema infectiosum) 4-14 7 days before rash until rash begins
Hand, foot, and mouth disease 3-6 Onset of mouth ulcers until fever gone
Impetigo (strep or staph) 2-5 Onset of sores until 24 hours on antibiotic
Lice 7 Onset of itch until 1 treatment
Measles 8-12 4 days before rash until 4 days after rash appears
Roseola 9-10 Onset of fever until rash gone (2 days)
Rubella (German measles) 14-21 7 days before rash until 5 days after rash appears
Scabies 30-45 Onset of rash until 1 treatment
Scarlet fever 3-6 Onset of fever or rash until 24 hours on antibiotic
Shingles (contagious for chicken pox) 14-16 Onset of rash until all sores have crusts (7 days) (Note: No need to isolate if sores can be kept covered.)
Warts 30-180 Minimally contagious
Respiratory Infections:  
Bronchiolitis 4-6 Onset of cough until 7 days
Colds 2-5 Onset of runny nose until fever gone
Cold sores (herpes) 2-12 Footnote 1
Coughs (viral) or croup (viral) 2-5 Onset of cough until fever gone
Diphtheria 2-5 Onset of sore throat until 4 days on antibiotic
Influenza 1-2 Onset of symptoms until fever gone
Sore throat, strep 2-5 Onset of sore throat until 24 hours on antibiotic
Sore throat, viral 2-5 Onset of sore throat until fever gone
Tuberculosis 6-24 months Until 2 weeks on drugs (Note: Most childhood TB is not contagious.)
Whooping cough 7-10 Onset of runny nose until 5 days on antibiotic
Intestinal Infections:  
Diarrhea, bacterial 1-5 Footnote 2 for Diarrhea Precautions
Diarrhea, giardia 7-28 Footnote 2 for Diarrhea Precautions
Diarrhea, traveler's 1-6 Footnote 2 for Diarrhea Precautions
Diarrhea, viral (Rotavirus) 1-3 Footnote 2 for Diarrhea Precautions
Hepatitis A 14-50 2 weeks before jaundice begins until jaundice resolved (7 days)
Pinworms 21-28 Minimally contagious, staying home is unnecessary
Vomiting, viral 2-5 Until vomiting stops
Other Infections:  
Infectious mononucleosis 30-50 Onset of fever until fever gone (7 days)
Meningitis, bacterial 2-10 7 days before symptoms until 24 hours on IV antibiotics in hospital
Mumps 12-25 5 days before swelling until swelling gone (7 days)
Pinkeye without pus (viral) 1-5 Mild infection, staying home is unnecessary
Pinkeye with pus (bacterial) 2-7 Onset of pus until 1 day on antibiotic eyedrops


  1. Cold sores: Less than 6 years old, contagious until cold sores are dry (4-5 days). No isolation if sores are on part of body that can be covered. More than 6 years old, no isolation necessary if beyond touching, picking stage.

  2. Diarrhea Precautions: Contagious until stools are formed. Stay home until fever is gone, diarrhea is mild, blood and mucus are gone, and toilet-trained child has control over loose BMs. Shigella and E-coli 0157 require extra precautions. Consult your day care provider regarding attendance restrictions.

Disclaimer:This information is not intended be a substitute for professional medical advice. It is provided for educational purposes only. You assume full responsibility for how you choose to use this information.

Author and Senior Reviewer: Barton D. Schmitt, M.D.

Copyright 1994-2015 Barton D. Schmitt, MD. All rights reserved.