Note: The legal status of cannabidiol to possess or purchase (in the US) is a muddy topic, and while not listed as a scheduled controlled substance, the US Drug Enforcement Administration (DEA) hasn’t provided a definite answer. Nothing in this answer should be construed as endorsing, approving, or recommending any activity that violates the law.
There do not appear to be any significant drug interactions that you need to worry about between spironolactone and CBD oil.
Marijuana contains hundreds of different compounds, but the big two are THC (tetrahydrocannabinol) and CBD (cannabidiol). CBD oil has skyrocketed in popularity for management of a wide range of conditions and issues. Both THC and CBD alter how your liver metabolizes certain drugs, and so they both produce drug interactions...sometimes significant ones.
However, spironolactone is not metabolized by the enzymes affected by THC or CBD, but by a completely different pathway. That doesn’t mean there is zero possibility of interaction between the two, but nothing that presents a risk to your health. That said, you may want to consider consulting on this topic with the physician who prescribes the spironolactone for you, if you feel comfortable doing so.
Please keep in mind that CBD oil, even without THC content, can significantly alter the way your liver metabolizes medications and other substances. This may not affect your spironolactone prescription, but it would be a wise move to check the interactions on any medication you are taking or plan to take while using CBD oil. While CBD oil itself is relatively benign, it can greatly increase or decrease the metabolism of other medications. This can result in your blood levels of that medication going too high (producing side effects/toxicity) or too low (resulting in reduced effectiveness).
Feel free to ask us again if you need more info. Thanks!