Antihistamines

The most widely used antihistamine to treat IC is hydroxyzine, which is also a mild anti-anxiety drug.  Some patients have reported a decrease in IC symptoms using other oral antihistamines, or medications with antihistamine properties, such as Claritin and Benadryl, or the newer leukotriene inhibitors such as Singulair.

Hydroxyzine
Hydroxyzine affects mast cell degranulation, which is thought to play a part in some IC patients’ symptoms, especially those who have a history of allergies, migraines and irritable bowel syndrome. Hydroxyzine has been shown to improve these conditions, as well as IC. Hydroxyzine has been found to decrease:

• Nocturia (night time voiding)
• Daytime frequency
• Pain (burning, pressure, painful intercourse)

Hydroxyzine is available in the following two oral forms:

• Generic name: hydroxyzine pamoate
  Brand name: Vistaril®
• Generic name: hydroxyzine hydrochloride
  Brand name: Atarax®

Hydroxyzine pamoate (Vistaril) has a slightly higher absorption rate. Hydroxyzine-HCL is a liquid form available for patients allergic to fillers or dyes used in the capsules or pills.
 
Dosage & Treatment Plan 
Most patients start with a 10 to 25 mg dosage of Atarax, Vistaril or their generic equivalent at bedtime every night for 1 week, and progress to 50 mg every night the second week. Ideally, within one month the dosage is increased to 75 mg, 50 mg taken at night and 25 mg taken during the day. Benefits of hydroxyzine may be seen within a few weeks to two months after initiating therapy.

To decrease the sedating side effects, some patients start hydroxyzine therapy at a 10 mg dosage, available with Atarax or in the liquid form, and work their way up, gradually, to a maximum dosage of 50 - 75 mg After one year some patients are able to decrease their dosage by one-half without increasing symptoms. Others report that upon reducing their dosage, symptoms will return within a few days.

Potential Side Effects

• sedation
• dry mouth
• increased depression in patients diagnosed with concurrent depression

Take this medicine early in the evening initially to avoid excessive morning drowsiness. Keep in mind that most patients report that any daytime drowsiness disappears within four to five days after beginning hydroxyzine therapy. Some patients report that with each dosage increase, the drowsiness period is shorter and not as intense.
 
Pregnancy & Warnings
Animal studies have found that fetal abnormalities occur at doses ten times higher than given to humans. It is not recommended that hydroxyzine be used if pregnant or nursing.

Hydroxyzine is contraindicated for use in epileptic patients.

 

Revised November 14, 2008