If you are just getting to know sea buckthorn oil, it makes sense to start with a small amount. This helps for two reasons: first, it lets you assess its characteristic tangy, fruity taste, which is quite pronounced and not familiar to everyone; second, it lets you check your individual tolerance.
A practical option is to add literally a few drops to a salad dressing or porridge and see how you like it, and then, if you wish, increase the portion to a comfortable amount. This makes it easier to find the quantity at which the berry note complements the dish rather than overpowering it.
The product is not consumed in case of hypersensitivity to its ingredients (sea buckthorn or sunflower oil), and if an allergic reaction occurs, stop using it and see a doctor. If you have chronic conditions, take medication, are pregnant or are breastfeeding, it makes sense to consult a specialist before using it regularly. The oil is a food product and an addition to a varied diet, not a substitute for balanced nutrition.