Mild or Delayed Allergic Reactions

As described by the name, mild or delayed allergic reactions present as a less severe reaction to allergens than anaphylaxis. They can occur as a reaction to such things as oral antibiotics, latex and (cold cure) acrylics. The signs and symptoms are limited to urticaria (itching), edema and erythema of the skin, mucosa and conjunctiva.

Treatment consists of:

  • Discontinuing the source of the allergy.
  • Administration of oral diphenhydramine at a dosage of 1 mg/kg every six hours for children or 25-50 mg for adults every 6 hours for 24 to 48 hours. Diphenhydramine is available in an oral form 12.5 mg/5 ml (see Table 2 for oral dosage by age) and 1 ml ampules or Min-i-jet (50 mg/ml) (Figure 4).5
Figure 4. Diphenhydramine Min-i-jet.
Image: Figure 4 depicts a packaging box for a Diphenhydramine Min-i-jet unit.
Table 2. Oral Diphenhydramine Liquid Dosing (12.5mg/5ml).
Age Dose
Under 3 months Consult physician
4-11 months (12-17 lbs) ¼ tsp every 4-6 hours
12-23 months (18-23 lbs) ½ tsp every 4-6 hours
2-3 years (24-35 lbs) ¾ tsp every 4-6 hours
4-5 years (36-47 lbs) 1 tsp every 4-6 hours
6-8 years (48-59 lbs) 1¼ tsp every 4-6 hours
9-10 years (60-71 lbs) 1½ tsp every 4-6 hours
11 yrs (71-95 lbs) 1¾ tsp every 4-6 hours
12+ years (96+ lbs) 2 tsp every 4-6 hours
Source: Benadryl package insert - dosing information. McNeil Consumer Healthcare Information