Although traditionally we think of epistaxis as a potential sign of hypertension, particularly when severe, whether hypertension causes epistaxis is unclear and even the association of these 2 conditions has been challenged in recent years.

A 2014 systematic review found that although the majority of studies reported an association between these 2 conditions, many did not include a control group, were of poor methodological quality and did not adjust for confounding variables such as age, sex, and anticoagulation¹.  Indeed, a larger study that controlled for many potential confounding factors failed to confirm such an association².  A small prospective study also found no correlation between the severity of hypertension and epistaxis³.

Even when an association between hypertension and epistaxis has been found, it is unclear how much of the stress of bleeding itself and white coat syndrome may affect the readings¹. However, an interesting 2017 study found masked hypertension (normal blood pressure in office, abnormal on ambulatory measurements) in 33.3% of patients with epistaxis with night time blood pressures that were significantly higher among patients with epistaxis⁴.

So the data is all over the place! It makes sense that long standing hypertension through its effects on blood vessels such as atherosclerosis and endothelium dysfunction may set the stage for epistaxis^1,5, particularly in our ever-aging population on anticoagulants.  But whether hypertension by itself is enough to cause epistaxis is likely to be debated for years to come.  

References

1. Kikidis D, Tsioufis K, Papanikolaou V, et al. Is epistaxis associated with arterial hypertension? A systematic review of the literature 2014;271:237-243. https://www.ncbi.nlm.nih.gov/pubmed/23539411
2. Fuchs FD, Moreira LB, Pires CP, et al. Absence of association between hypertension and epistaxis: a population-based study. Blood Press 12:145-48. http://www.tandfonline.com/doi/abs/10.1080/08037050310001750
3. Knopfholz J, Lima-Junior E, Précoma-Neto D, et al. Association between epistaxis and hypertension: A one year follow-up after an index episode of nose bleeding in hypertensive patients. Internat J Cardiol 2009;134:e107-e109. https://www.ncbi.nlm.nih.gov/pubmed/18499285
4. Acar B, Yavuz B, Yildiz E, et al. A possible cause of epistaxis: increased masked hypertension prevalence in patients with epistaxis. Braz J Otorhinolaryngol 2017;83:45-49. http://www.scielo.br/pdf/bjorl/v83n1/1808-8694-bjorl-83-01-0045.pdf
5. Celik T, Iyisoy A, Yuksel UC, et al. A new evidence of end-organ damage in the patients with arterial hypertension: epistaxis? Internat J Cardiol 2008;141:105-107. https://www.ncbi.nlm.nih.gov/pubmed/19138805