Background: The immune mechanism involved in the reaction to hydrochlorothiazide, which is widely used to control hypertension, is unknown. The short latency period between the take of the drug and the onset of symptoms suggests immediate hypersensitivity.Case report: 63-year-old woman with arterial hypertension who, on three occasions, experienced nausea, vomiting, general malaise, shivering, arthralgias, dysthermic sensation, back pain of mechanical characteristics and mild non-productive cough, as well as fever and chest tightness with increased dyspnea and desaturation of up to 88 %, after taking hydrochlorothiazide.Conclusions: Clinical presentation in the patient was similar to a septic shock, which is a rare allergic reaction. The diagnosis has to be clinical. This type of reaction might be due to type III hypersensitivity owing to the formation of immune complexes. Avoiding of the culprit drug is key to a good evolution.

Tree pollen is the most abundant in the Community of Madrid (CAM), and specifically, pollen types from Olea, Cupressaceae, and Platanus are the most allergenic, after Gramineae, in this Spanish region. Air pollutants are one of the most significant stress factors for wind-pollinated vegetation, especially in urban areas, and can cause alterations in the immune system and the consequent triggering of type I hypersensitivity reactions mediated by immunoglobulin E (IgE). This study analyses the allergic sensitization caused by the interrelation of O₃, NO₂, and PM₁₀ pollutants with the tree pollen types Olea, Cupressaceae, and Platanus in the period 2017–2021. To this end, general linear models were calculated using the Statgraphics Centurion 19 tool. The data collected came from the Air Quality Networks of the CAM and Madrid City Council, the CAM Palynological Network, and the Allergy Services of the reference hospitals in the five study areas. This research confirms a statistically significant correlation between allergic sensitivity to pollen types and their concentrations in the air, and those of atmospheric pollutants, in the different areas and years studied. These pollen and pollutant concentrations in the atmosphere of the CAM jointly influence the prevalence of allergic sensitisation, as is evident in all the models calculated.