I have seen high blood pressure (170 to 190 systolic) (without MAO intake) in a patient drinking several servings a day (more than 20), of our argentinian traditional beverage called "Mate". This is a green infusion which is known to have a caffein content twice the one found in coffee. His BP became normal after quitting mate.
Severe Hypertension Linked to Caffeine-MAO Inhibitor Interaction — Physician’s First Watch
Severe Hypertension Linked to Caffeine-MAO Inhibitor Interaction
By Amy Orciari Herman
High caffeine intake, when combined with monoamine oxidase (MAO) inhibitor therapy, can lead to severe hypertension, according to a research letter in the Annals of Internal Medicine.
Dutch researchers describe a middle-aged man who developed severe hypertension (220/119 mm Hg) after starting treatment with the MAO inhibitor tranylcypromine. The patient's blood pressure and heart rate peaked twice a day after tranylcypromine intake (previously, his blood pressure had been well controlled with hydrochlorothiazide). The patient's exam findings were otherwise normal. However, he reported drinking 10 to 12 cups of caffeinated coffee daily for years.
The patient stopped drinking coffee but continued tranylcypromine. Two weeks later, his blood pressure had normalized. When he began drinking decaf (10-12 cups/day), his blood pressure remained stable.
The authors note that caffeine has previously been shown to inhibit MAO and thus "might supplement the effects of MAO inhibitors." They conclude that providers "should consider limiting caffeine consumption" in patients with high intake who are using MAO inhibitors.