• Increasing use of OTC meds is a worldwide occurence with $3.5 billion each year spent in the US.
• About 4 million children younger than 12 yrs are treated with these meds each week in the US.
• In 2007 the FDA recommended that the use of OTC cold meds (antihistamines-brompheniramine, chlorpheniramine, diphenhydramine, doxylamine; antitussive-dextromethorphan; expectorant-guaifenesin; and decongestants-pseudoephedrine and phenylephrine) be prohibited in children < 6 yrs.
• A recent review of 103 childhood deaths due to OTC meds found that most deaths were from product misuse rather than adverse effects resulting from recommended doses particularly when the product was used with the intent to sedate a child. 
• Children less than 2 years old were most susceptible to death using these products which is why manufacturers voluntarily withdrew the use of OTC meds in this age group.

References

Dart R., Paul I., et al.  Pediatric Fatalities Associated with OTC (nonprescription) cough and cold medications.  Annals of Emergency Medicine. April 2009. Vol 53, No. 4 p 411-417