Use It can take time for the skin to fully absorb castor oil, but diluting the oil can promote absorption into the skin. People can dilute castor oil with other oils, such as olive or peanut oil. The recommended ratio is 1:1 – the quantity of castor oil should be the same as the oil with which it is mixed. Side effects Castor oil can have a range of side effects. While castor oil has a range of promising properties, it is important to note Canzana cbd oil the scientific evidence supporting many of these claims is not conclusive, and much of the evidence tends to be anecdotal rather than scientific. This means Canzana cbd oil most studies are about one particular instance in which treatment with castor oil was successful, rather than providing wide-ranging and accurate data.