Is diphenhydramine a safe option for an 8-month-old infant with a rash after ingesting peanut butter, potentially indicating an allergic reaction?

From the Guidelines

Diphenhydramine can be used for an 8-month-old with a rash after peanut butter exposure, but you should first call your pediatrician or seek emergency care immediately. For mild allergic reactions, liquid diphenhydramine can be given at a dose of 1.25 ml (6.25 mg) for an 8-month-old (based on the typical weight of 16-20 pounds), using the children's liquid formulation (12.5 mg/5 ml) 1. However, a rash after peanut butter exposure could indicate a food allergy, which can potentially progress to a severe allergic reaction. Watch for concerning symptoms like facial swelling, difficulty breathing, vomiting, or lethargy. If these occur, call 911 immediately. After this incident, avoid giving peanut products until your child can be evaluated by a pediatrician or allergist.

Some key points to consider when introducing peanuts to infants include:

• Food containing peanuts should be introduced into the diet of infants four to six months of age who have severe eczema, egg allergy, or both 1.
• Peanut-specific immunoglobulin E should be measured or a skin prick test performed before introducing peanuts in high-risk groups 1.
• If an infant has mild to moderate eczema, foods with peanuts can be given at approximately six months of age 1.

It's also important to note that diphenhydramine works by blocking histamine receptors to reduce allergic symptoms, but it can cause drowsiness and should be used cautiously in infants 1. Always measure doses precisely using the provided measuring device, not household spoons. According to the addendum guidelines for the prevention of peanut allergy in the United States, infants with peanut-specific IgE < 0.35 kUA/L or with a peanut SPT ≤2mm have dietary peanut introduced as early as 4 to 6 months of age without a need for further evaluation 1.

From the FDA Drug Label

Warnings Do not use • to make a child sleepy • with any other product containing diphenhydramine, even one used on skin Ask a doctor before use if you have • a breathing problem such as chronic bronchitis • glaucoma • trouble urinating due to enlarged prostate gland Ask a doctor or pharmacist before use if you are taking sedatives or tranquilizers When using this product • marked drowsiness may occur • avoid alcoholic drinks • alcohol, sedatives, and traquilizers may increase drowsiness • be careful when driving a motor vehicle or operating machinery • excitability may occur, especially in children If pregnant or breast-feeding, ask a healthcare professional before use Keep out of reach of children. In case of accidental overdose, get medical help or contact a Poison Control Center right away (1-800-222-1222)

The use of diphenhydramine in an 8-month-old child with a rash after peanut butter is not recommended without consulting a doctor. The label warns that excitability may occur, especially in children, and it advises to ask a doctor before use if the patient has certain conditions. Since the child is only 8 months old, it is crucial to consult a healthcare professional before administering diphenhydramine 2.

From the Research

Management of Peanut Allergy

• The management of peanut allergy involves strict avoidance, prompt recognition of allergic reactions, and rapid initiation of epinephrine and other supportive therapy for anaphylaxis 3.
• Current advice for patients with peanut and nut allergy includes providing an epinephrine injector, as well as training and advice on nut avoidance and emergency medication 4.

Treatment of Allergic Reactions

• Oral antihistamines, such as diphenhydramine, may be used to treat mild allergic reactions, including cutaneous symptoms 4.
• Inhaled epinephrine may be effective for early laryngeal edema, while an epinephrine injector is recommended for severe reactions 4.
• The use of epinephrine-treated reactions during peanut oral immunotherapy has been reported, with a success rate of 85% in achieving the target maintenance dose 5.

Introduction of Peanut in Infancy

• Introduction of peanut at ≥8 months in infants with moderate and severe eczema may result in an increased risk of reactions to peanut 6.
• It is suggested that peanut should be introduced before the age of 8 months to reduce the risk of reactions at first exposure in infants with moderate and severe eczema 6.

Safety of Diphenhydramine

• While diphenhydramine may be used to treat mild allergic reactions, its safety and efficacy in infants, particularly those with eczema, should be considered 4, 6.
• However, there is limited information available on the specific use of diphenhydramine in 8-month-old infants with a small rash after peanut butter consumption.