5-7

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5-7. ANTIPRURITIC AGENTS

a. General. Itching (pruritus) routinely accompanies many skin disorders. Itching may be a symptom of a disease which affects the person's entire system; in liver damage, for example, circulating bile salts cause itching all over the body. Persons suffering from allergic reactions, blood disorders, and various psychologic disturbances frequently experience itching. There are some simple antipruritics (agents which give relief to itching, burning, pain) to help the patient avoid scratching and possibly causing a secondary bacterial infection. Hot baths, heavy bed clothing, and rubbing of the skin should be avoided because heat will cause the capillaries to get bigger in turn increasing the itching feeling.

b. Local Anesthetics. Local anesthetics can be applied to a rather small area and act to block or interfere with itching, burning, or pain by interfering with those sensations. Here are three local anesthetics:

(1) Dibucaine. Dibucaine is a potent, toxic, long-acting local anesthetic used in ointments for relief of pain. About 15 times as potent and toxic as procaine (a mild medication), its anesthetic action lasts about three times as long as procaine.

 

(2) Benzocaine. This medication is also a local anesthetic, but benzocaine is available in sprays, powders, and creams. Because it does not mix well with water, benzocaine is absorbed into the skin slowly and is not toxic. The medication can be applied directly to an open wound or ulcerated surface and will stay in place doing its work of relieving pain for a long time.

 

(3) Lidocaine. Lidocaine is available in jelly form. This drug has a faster, more intense, and longer lasting effect (relief of pruritus) than an equal concentration of procaine.

c. Phenol One Percent. Phenol is a substance obtained from coal and used as an anesthetic and disinfectant. Phenol is often combined with other substances because its anesthetic property will stop itching and also act as a disinfectant. A one to five percent solution of cresol that contains phenol is sometimes used to disinfect skin. The compound Resorcinol (one percent phenol) is used to treat skin diseases such as eczema, seborrhea of the scalp, ringworm, and psoriasis.

d. Menthol/Camphor. Menthol provides a sensation of coolness by acting on the skin's receptors. The concentration used should be one-tenth percent to one-twenty-fifth percent. Camphor in a concentration of 0.5 percent to one percent provides a sensation of coolness on the skin by evaporation. Both menthol and camphor in medications are soothing to the skin.

e. Boric Acid Solution. Boric acid may be used in the form of solution, ointment, or dusting powder. A two percent boric acid solution used on a wet pack is very effective in relieving itching, burning, and pain of skin lesions. Additionally, boric acid solution acts as a disinfectant. Boric acid solution may be prescribed in water or in normal saline solution.

f. Cool Starch Baths. Two cups of starch to a bathtub of warm water can reduce pruritus. Caution the patient to be careful getting in or out of the bathtub because the starch can make the tub slippery.

g. Diphenhydramine (Benadryl^®). Benadryl is an antihistamine used primarily in allergic reactions. This drug is a general preparation used for its antihistamine properties. It is useful in relieving bronchial spasms as well as serum reactions, urticaria, and drug reactions.

h. Calamine Lotion, Phenolated and Mentholated. This product is used as an astringent (an agent to dry mucous secretions, shrink skin, reduce inflammation of mucous membranes, promote healing, toughen skin) and as a protectant. Both these actions aid in reducing inflammation associated with insect bites, poison ivy, and sunburn. Phenol and menthol may be added to calamine lotion to produce an antipruritic (relieve itching) effect. Tell the patient using this product that the preparation is for external use only. The lotion must be shaken well before using it. Calamine lotion is soothing and drying. It may be applied locally three to four times daily or as needed for acute skin problems. Avoid using this medication for long periods of time; such use causes excessive drying.

i. Oatmeal. A commercial preparation of colloidal oatmeal or just oatmeal from the grocery store cereal section may be used in a bath as a soothing, cleansing, and anti-itching agent. An oatmeal bath is recommended for itching, hives, sunburn, poison ivy, prickly heat, diaper rash, and chapped skin. Add one cupful and soak in the tub for 30 minutes to one hour. Pat the skin dry with a towel; do not rub the skin. The oatmeal, whether in regular or colloidal form, makes the bath tub very slippery so caution patients to be careful when getting in or out of the bathtub.

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