I started full body internal itching after taking 10 days of Sing...

did you have your C-S diagnosis before or after you started singulair?

: Ned Tijdschr Geneeskd. 2008 Mar 1;152(9):513-7.Links

Gielen CL, van't Wout JW.
A 75-year-old woman with a history of asthma, rhinitis and nasal polyps was admitted due to petechial lesions on the lower left leg and weakness of the right foot. Six weeks prior to admission, she had started treatment with montelukast 10 mg daily. Based on the asthma, eosinophilia, mononeuritis of the right leg and a skin biopsy showing small vessel vasculitis with eosinophilic granulocytes, the patient was diagnosed with Churg-Strauss syndrome (CSS). After consulting with the pulmonologist, montelukast therapy was discontinued and replaced with a combined preparation of a parasympatholytic and a P2-sympathomimetic. The patient was also given prednisone 60 mg daily, which resulted in prompt clinical improvement and resolution of the eosinophilia. Development of CSS has been associated with the use of montelukast and should be considered in patients with asthma who develop new symptoms, such as neuritis, vasculitis of the skin or pulmonary infiltrates with an increase in eosinophilia during montelukast therapy. In these patients, treatment with montelukast should be discontinued, although whether a causal relationship exists between montelukast and CSS continues to be debated in the literature.

PMID: 18389887