Medscape Reference [On-line information]. Your questions will be answered by a laboratory scientist as part of a voluntary service provided by one of our partners, American Society for Clinical Laboratory Science. For professional medical information on natural medicines, see Natural Medicines Comprehensive Database Professional Version.WebMD does not provide medical advice, diagnosis or treatment.This survey is being conducted by the WebMD marketing sciences department.All information will be used in a manner consistent with the WebMD Hydroxyzine is an antihistamine that can treat dogs for allergic reactions, though it also has properties that treat nausea, anxiety, and other conditions. If a sample is drawn too late, results may be normal. Available online through http://www.merckmanuals.com. Accessed on 02/18/17.Hogan, D. and Mastrodomenico, C. (2016 August 8, Updated). St. John's wort can increase how fast the body gets rid of alprazolam (Xanax). Taking St. John's wort along with some medications that are broken down by the liver can decrease the effectiveness of some medications. Accessed August 2012.Peavy, R. and Metcalfe, D. (2008 September 22). Before taking St. John's wort talk to your healthcare provider if you take any medications that are changed by the liver.St. Available online at http://www.aafp.org/afp/2003/1001/p1325.html. If testing is done for other conditions, you may be instructed to refrain from taking Anaphylaxis is usually diagnosed clinically, but a histamine test may be used along with a Instead of a blood test, a histamine test performed on urine collected over a 24-hour period may be ordered instead to evaluate histamine production over a longer time frame. Available online at http://www.arupconsult.com/Topics/MastCellDz.html?client_ID=LTD#tabs=0. This might decrease the effectiveness of some medications.Some medications can increase sensitivity to sunlight. This coordinated activity is regulated by the central and peripheral nervous systems. John's wort increases a brain chemical called serotonin. Anaphylaxis. Anaphylaxis.

St. John's wort might increase how quickly the body breaks down cyclosporine (Neoral, Sandimmune). Information from this source is evidence-based and objective, and without commercial influence.

If you take birth control pills along with St. John's wort, use an additional form of birth control such as a condom.The body breaks down cyclosporine (Neoral, Sandimmune) to get rid of it. As professional clinical laboratory scientists, our goal is to assist you in understanding the purpose of laboratory tests and the general meaning of your laboratory results. St. John's wort might increase how quickly the body gets rid of imatinib (Gleevec). Anaphylaxis. In addition to allergic reactions, histamine plays a role in inflammatory processes, stimulates gastric acid secretion, acts as a neurotransmitter (chemical substance that transmits messages between nerve cells), dilates blood vessels, increases vascular permeability (allows fluids to move through blood vessel walls), affects smooth muscle contraction in the intestines and lungs, and affects heart rate and contraction. This chemical is called serotonin.
Taking St. John's wort along with aminolevulinic acid might increase the chances of sunburn, blistering or rashes on areas of skin exposed to sunlight.

Values that are outside expected ranges can provide clues to help identify possible conditions or diseases.While accuracy of laboratory testing has significantly evolved over the past few decades, some lab-to-lab variability can occur due to differences in testing equipment, chemical reagents, and techniques. St. John's wort might decrease how quickly the body gets rid of fexofenadine. Their meaning comes from comparison to reference ranges. When you experience a severe allergic reaction, you may experience anaphylaxis. Be sure to wear sunblock and protective clothing when spending time in the sun.St. However, you are currently at Lab Tests Online. Histamine and histamine intolerance1,2,3. When you have symptoms such as flushing, nausea, throat swelling or low blood pressure that may be due to a life-threatening allergic reaction; sometimes when your healthcare practitioner suspects that you have mastocytosis or mast cell activationNone for anaphylaxis, but timing of the sample very soon after the beginning of symptoms is important. v1;68(7).
World Allergy Organization Guidelines for the Assessment and Management of Anaphylaxis. Taking St. John's wort might increase how quickly the body breaks down these medications. St. John's wort might increase how quickly the liver breaks down some medications. Available online at https://arupconsult.com/content/mast-cell-disorders Accessed on 02/18/17.Delgado, J. Available online at http://emedicine.medscape.com/article/2093933-overview#showall. Available online at https://arupconsult.com/content/anaphylaxis. Accessed on 02/18/17.Onnes, M. et.al.

Meperidine (Demerol) can also increase serotonin in the brain.

It is important to know that you must use the range supplied by the laboratory that performed your test to evaluate whether your results are "within normal limits.