There are two sides to every man-made or mainstream medicine: the good, beneficial effects targeting illness and disease, and the bad, off-target effects, commonly known as side effects. Most of the time, the side effects of acute doses are minimal, low risk, and the benefits largely outweigh the costs.
But, especially in the case of chronic medication, medicines trigger such challenging side effects that it's no longer tenable for the patient to continue using them. In the case of powerful anti-cancer chemotherapies, the severe associated side effects require co-therapies to keep the side effects in check.
Aversion to side effects has led many people to turn toward cannabidiol (CBD) as a complementary or alternative therapy. Cannabidiol, widely used as a self-prescribed therapy for a wide variety of ailments, is an all-natural substance, and it's easy to assume there is absolutely zero risk of CBD oil side effects. Does this mean CBD has no side-effects at all? Also, what do people need to know about CBD’s side effects prior to taking it as a viable alternative to mainstream medicine?
What Are the Common CBD Oil Side Effects?
For everyone already on the CBD bandwagon, rest easy. The known CBD side effects remain considerably less problematic and lower in risk than many of its pharmaceutical counterparts. Even under the intense scientific scrutiny, CBD is going through these days, with researchers stating that more clinically and statistically robust study on the topic is needed, CBD shows little to no risk of side effects under most circumstances. This is even true with higher doses of up to 1,500 mg a day. Studies have shown high doses are generally well tolerated by humans.
Unlike its sister cannabinoid, THC, CBD does not trigger any psychoactivity, nor does it seem to raise blood pressure or body temperature. In fact, a small recent study has shown CBD to lower blood pressure in humans. THC is a different story, though, as users sometimes have adverse reactions to it in high doses. This is simply because the "high" is much too powerful or they experience psychological effects that are too much to handle, such as psychosis.
CBD tends to promote, at the very least, a sensation of relaxation. It can be said that a sense of calm is technically a CBD oil side effect, and is generally considered a positive one. This positive CBD side effect has led researchers to study CBD oil’s effect on social anxiety and other general anxiety disorders, with promising results.
Other common and relatively low-risk CBD oil side effects are tiredness, diarrhea, and changes in weight and appetite. Again, these were found through an examination on the current body of human-based study, mostly on CBD and epilepsy or psychotic disorders. These CBD oil side effects are minor, but if they occur, they can become challenging for some. It's crucial to be aware of both sides of the coin, the good and bad, before commencing any new treatment.
CBD Oil Side Effects in Combination with other Pharmaceuticals
As said, cannabidiol has so far proven relatively safe to use under most circumstances, even in high doses. But, preliminary laboratory evidence suggests it can interact with some pharmaceuticals, specifically hepatic drugs, or those metabolized by the liver.
According to the laboratory research, at sufficient dosages, CBD seems to temporarily interact with some cytochrome P450 enzymes, which are excreted by the liver, and which are in charge of metabolizing most marketed pharmaceuticals. This research is still in the very early stages, yet scientists are already seeing, mostly in animal or laboratory studies, that CBD’s interaction with P450 enzymes reduces or potentiates the effects of other drugs for a period of time.
What does this mean for you? CBD’s action in the liver depends on how much, and how it is administered, also on the user’s unique physiology. Isolated or whole-cannabis consumption also plays a role in this complex process. In low doses, CBD is not likely to have much effect on enzymatic activity, and if inhaled, it doesn’t seem to have an effect on the liver enzymes.
As we’ve seen, there are few studies into this potential CBD oil side effect. If the early research proves to be true, that CBD could increase the toxicity of other hepatic drugs, precautions are in order. Anyone seeking out CBD as a complimentary or co-therapy to their current regime of pharmaceuticals should speak with a doctor beforehand. If CBD slows down the metabolization process of other drugs, physicians may wish to monitor blood-levels for a pattern of increased toxicity.
CBD and the Immune System
Yet, this inhibitory effect that CBD has on the P450 enzymatic system a double-edged sword. In some cases, this is why someone chooses to use CBD, while in other cases it might be considered a problematic CBD oil side effect.
The available data from in-vitro and in-vivo methods of one study (published in 2011, entitled Safety and Side Effects of Cannabidiol, a Cannabis sativa Constituent), demonstrate that CBD might inhibit the full function of the immune system. For those suffering from an autoimmune disorder like rheumatoid arthritis, Hashimoto's thyroiditis, lupus and more, inhibiting the function of the overactive immune system may be a very good thing. On the other hand, for people already challenged by a compromised immune system, introducing a compound which inhibits its function could worsen the disease.
The authors of this study also report that “some results suggested that CBD could yield a [two phase] response in the immune system with stimulatory capacity at lower doses [...] and inhibitory activity at higher doses.” Clearly, CBD oil side effects on the immune system are nuanced and require follow up study. 
CBD Treatment: A Personal Decision
The fact that CBD side effects are low risk and occur rarely is exactly why many people are turning toward it as an alternative treatment. Cannabidiol’s effects, both positive and negative, need to be confirmed through large-scale clinical study before concrete advice is available.
It’s ultimately a personal decision to determine if CBD oil is right for you. Do the benefits outweigh the possible negative consequences? Thousands of people already self-medicating with CBD oil will attest to their positive personal experiences. For these people, any CBD oil side effects are negligible at best.
A Final Note on CBD Quality
Perhaps due to the explosion of the cannabinoid market, it now includes disreputable sources. Although it's true that these companies may have the best intentions, their products nevertheless could be the source of some side effects.
Sourcing high-quality CBD oil means sourcing products where the producers are conscious of each step of the process. This means finding CBD oil grown organically, and away from possibly toxic contaminants. It involves using CO2 extraction instead of relying on potentially harmful solvents. It also means having third-party lab results publicly available to confirm the purity.
Sourcing high-quality CBD oil from reputable companies is one way to reduce the risk of side effects. Listening to what your body has to say as you explore CBD is a vital step on your road to recovery.