Itching: diphenhydramine

Skin management topical agents used for bums (1% silver sulfadiazine), antibiotics for secondary infections (Neosporin ), antihistamines for itching (diphenhydramine Img/kg/dose orally q6-8h max 300mg/day, hydroxyzine 0.5mg/kg/dose orally q6-8h)... 

Angioedema may be precipitated by histamine release but appears to be maintained by peptide kinins that are not affected by antihistaminic agents. For atopic dermatitis, antihistaminic drugs such as diphenhydramine are used mostly for their sedative side effect, which reduces awareness of itching. 

Drying lotions should not be used on skin lesions because they may increase scarring. In the child or adult for whom the skin lesions itch or are irritating, an oral antihistamine may help to prevent scratching, which can lead to secondary infection and thereby scarring. Recommended agents include oral chlorpheniramine or diphenhydramine.The use of cimetidine is controversial as an H2 blocker, oral cimetidine has an immunosuppressive action. The effects are not always consistent, however, and use of cimetidine is risky in autoimmune disorders and organ transplant patients. 

Oral antihistamines can be effective in alleviating the itch as well as assisting in the resolution of the wheals. When urticaria or angioedema has a severe presentation, diphenhydramine or oral steroids can be effective. 

Adverse reactions to human serum albumin are uncommon and usually mild, such as itching and urticaria. Serious reactions are rare. A patient who has reacted violently to albumin on one occasion may tolerate it well on another after being given an antihistamine such as diphenhydramine (1). Aggregates present in protein preparations may be the cause of some reactions. Another postulated cause may be the presence of antibodies against genetic variants of human albumin (2). Hypotensive reactions due to the presence of a prekallikrein activator in some batches of formulations can occur. 

Nerve blocks can be given in cases of very painful outbreaks. A mixture of lidocaine with adrenaline (epinephrine) and ropivacaine or bupivacaine" can be used. In some cases, the doctor will have to prescribe opioids to relieve severe pain. However, treatment with opioids might well get rid of the pain but will not affect the itching. It could even aggravate the pruritus. The itching sometimes resists hydroxyzine and diphenhydramine. Asken reported that he once had to inject propanolol intravenously to relieve unbearable pruritus. 

Antihistamines are used to attempt to break the itch-scratch cycle that results from the pruritus of AD. Despite frequent use of antihistamines, few clinical studies support their efficacy, most likely because not all pruritus is mediated by histamine. Because pruritus is worse at night, the sedating antihistamines (i.e., hydroxyzine or diphenhydramine) can offer an advantage by facilitating sleep, whereas the newer nonsedating antihistamines have shown variable results. 

Itching may respond to treatment with antihistamines (hydroxyzine or diphenhydramine) emollient skin creams or occlusive agents are effective for dry, peeling skin avoid corticosteroids may counteract the antitumor effects ofIL-2. 

At the first sign of contact dermatitis, clean the skin area immediately. Patch testing may be needed to determine the causative factor. Apply wet dressings containing Burow s solution (aluminum acetate), lotions such as calamine that contain zinc oxide, calcium hydroxide solution, and glycerin. Calamine lotion may contain the antihistamine diphenhydramine and is used primarily for plant irritations. If itching persists, antipraritics (topical or systemic diphenhydramine [Benadryl]) may be used. Topical antipraritics should not be applied to open wounds or near the eyes or genital area. 

Many water-insoluble amines with useful medicinal properties are sold as their water-soluble ammonium salts, which are more easily transported through the body in the aqueous medium of the blood. Benadryl, formed by treating diphenhydramine with HCI, is an over-the-counter antihistamine that is used to relieve the itch and irritation of skin rashes and hives. 

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