This is brought on by the action of the mediators. If the drop in blood pressure is drastic and sudden, it can lead to unconsciousness, even cardiac arrest and death. Signs or symptoms of an allergic reaction include any, some, or most of the following:Pores and skin: irritation, inflammation, itching, swelling, blistering, weeping, crusting, rash, eruptions, or hives Lung area: wheezing, tightness, cough, or shortness of breathHead: swelling or bumps on the facial skin and neck, eyelids, lips, tongue, or throat, hoarseness of tone of voice, headacheNose: stuffy nose, runny nose , sneezingEyes: crimson , itchy, swollen, or watery or swelling of the area around the face and eyesStomach: pain, nausea, vomiting, diarrhea, or bloody diarrheaOther: fatigue, sore throat..In broad conditions, there are two types of stem cells, embryonic stem cells and adult stem cells. Human being embryonic stem cells are isolated from a 4 – to 5-day-outdated postfertilization blastocyst . Adult stem cells can be found in tissues throughout the body and work as a reservoir to replace damaged or maturing cells. Richard K. Burt, M.D., of the Northwestern University Feinberg College of Medicine, Chicago, and co-workers conducted a review of articles regarding clinical indications and outcomes for usage of bloodstream – and bone marrow-derived stem cells. A search of databases identified 323 reports which were examined for toxicity and feasibility, and 69 which were evaluated for outcomes.