What are the guidelines for the use of antihistamines (anti-histamine medications) in children less than 2 years old?

Antihistamine Use in Children Under 2 Years Old

Antihistamines should generally be avoided in children under 2 years of age due to safety concerns, with no over-the-counter antihistamines recommended for this age group. 1, 2

Safety Concerns and Guidelines

• The FDA and pediatric advisory committees recommend against using OTC cough and cold medications (including antihistamines) in children under 6 years of age due to significant safety concerns 1
• FDA-approved labeling for diphenhydramine (a first-generation antihistamine) explicitly states "Do not use" for children under 6 years of age 2
• Between 1969 and 2006, there were 69 fatalities associated with antihistamines in children under 6 years, with 41 reported in children under 2 years 1
• Common causes of serious adverse events include:
  • Drug overdose
  • Medication errors
  • Accidental exposures
  • Use of multiple cold/cough products simultaneously 1

First vs. Second Generation Antihistamines

First-Generation Antihistamines

• Not recommended for children under 2 years due to:
  • Significant sedation (occurs in >50% of patients) 3
  • Impaired learning ability 3
  • Risk of accidental overdose 4
  • Potential cardiotoxicity in overdose 3
  • Antimuscarinic side effects 5

Second-Generation Antihistamines

• Have better safety profiles than first-generation antihistamines 5, 3
• Some second-generation antihistamines (cetirizine, desloratadine, fexofenadine, levocetirizine, and loratadine) have been shown to be well-tolerated in young children 1
• However, most are not FDA-approved for children under 2 years 6

Specific Antihistamine Options

When antihistamines must be used in children under 2 years (in exceptional circumstances and under medical supervision):

• Cetirizine and loratadine are the only second-generation antihistamines approved for children under 5 years in some countries 7
• Dosing must be carefully adjusted based on:
  • Age and weight
  • Renal function (cetirizine dose should be halved in moderate renal impairment) 8
  • Hepatic function

Common Pitfalls to Avoid

1. Using OTC antihistamines without medical supervision in children under 2 years
2. Administering adult doses to young children
3. Combining multiple products containing antihistamines
4. Using first-generation antihistamines when second-generation options are available
5. Not recognizing signs of overdose including:
   • Excessive sedation
   • Paradoxical excitation
   • Respiratory depression
   • Cardiovascular effects

When Medical Consultation is Required

• Always consult a physician before administering any antihistamine to a child under 2 years 8
• Seek immediate medical attention for any adverse reactions
• Emergency care is needed for suspected overdose

In summary, antihistamines should generally be avoided in children under 2 years of age unless specifically prescribed by a physician, with second-generation antihistamines preferred when treatment is necessary due to their better safety profile.