Does hrt including testosterone cause blotchy inflamed cheeks and thread veins on face ? antihistamine seems to help but i dont want to take them permanently, would like to find the root cause. many thanks?

Having a GP or Dermatologist assess the cheeks and face veins would help with this. This may be rosacea with many treatment options: reducing triggers (sun spicy-foods), laser light, brimonidine, topical metronidazole. With the right diagnosis and treatment, the cheeks and face can return to their healthy state. https://www.health.harvard.edu/womens-health/rosacea-can-flare-at-menopause