Many common anti-allergy medications are useful because they reduce the mast cells ability to react to histamine.At least one clinical study suggested that nifedipine, a calcium channel blocker used to treat high blood pressure, may reduce mast cell degranulation in patients with urticaria pigmentosa. A 1984 study by Fairly et al. included a patient with symptomatic urticaria pigmentosa who responded to nifedipine at dose of 10 mg po tid. However, nifedipine has never been approved by the FDA for treatment of urticaria pigmentosa. Another mast cell stabilizer Gastrocrom, a form of cromoglicic acid has also been used to reduce mast cell degranulation. Epidemiology
Urticaria pigmentosa is a rare disease, affecting fewer than 200,000 people in the United States. See also
Urticaria
Dermatographic urticaria
Generalized eruption of cutaneous mastocytosis (adult type)

References
Further reading
Alto WA, Clarcq L (June 1999). "Cutaneous and systemic manifestations of mastocytosis". Am Fam Physician. 59 (11): 3047–54, 3059–60. PMID 10392589. == External links ==
Other causes of similar symptoms that should be considered include seizure, stroke, concussion, low blood oxygen, low blood sugar, drug intoxication and some psychiatric disorders among others. Treatment depends on the underlying cause. Those who are considered at high risk following investigation may be admitted to hospital for further monitoring of the heart.A hemoglobin count may indicate anemia or blood loss. However, this has been useful in only about 5% of people evaluated for fainting. The tilt table test is performed to elicit orthostatic syncope secondary to autonomic dysfunction (neurogenic). A number of factors make a heart related cause more likely including age over 35, prior atrial fibrillation, and turning blue during the event. Electrocardiogram
Electrocardiogram (ECG) finds that should be looked for include signs of heart ischemia, arrhythmias, atrioventricular blocks, a long QT, a short PR, Brugada syndrome, signs of hypertrophic obstructive cardiomyopathy (HOCM), and signs of arrhythmogenic right ventricular dysplasia (ARVD/C). Signs of HCM include large voltages in the precordial leads, repolarization abnormalities, and a wide QRS with a slurred upstroke. Signs of ARVD/C include T wave inversion and epsilon waves in lead V1 to V3.It is estimated that from 20 to 50% of people have an abnormal ECG. However, while an ECG may identify conditions such as atrial fibrillation, heart block, or a new or old heart attack, it typically does not provide a definite diagnosis for the underlying cause for fainting. Sometimes, a Holter monitor may be used.