According to the Mayo Clinic is well-tolerated in most people. In addition, most of the side effects are relatively mild and do not present a real risk for most people and can be easily dealt with. For example, the most common side effects reported are dry mouth, diarrhea, a decreased appetite, drowsiness and fatigue. Drowsiness and fatigue may be the most problematic side effects—but only if you drive or operate heavy equipment, not if you are in bed and asleep.
CBD is a non-intoxicating cannabinoid derived from hemp—a “cousin” of the cannabis plant. It will not get you “high”.
CBD has been used to reduce pain, depression, anxiety, act as an anti-inflammatory and help normalize sleep patterns, muscle spasms, seizures, blood sugar and blood pressure. , 
For the most part, the side effects of CBD are often the desired effects (eg. drowsiness or a decreased appetite) or easily remedied by drinking water, adding fiber to your diet or laying down for a nap.
The bigger concern, frankly, is the safety of the product that you buy. Let’s get into how you can ensure you are buying the best and the safest CBD!
Research indicates that most people tolerate CBD very well. The side effects noted above—dry mouth, diarrhea, a decreased appetite, drowsiness and fatigue—are all relatively mild, relatively rare and generally are short-lived. You can probably avoid most of them by following the mantra: Start low and Go Slow—by starting at a very low dose and increasing that amount until you achieve your goals. Also—if you experience any side effects, stop taking the CBD.
Most of the more significant and disturbing side effects experienced by people have less to do with CBD and much more to do with contaminants like heavy metals or microbial toxins in the product. There also have been some scattered reports of changes in male fertility, interactions with prescription medications and liver damage.  The FDA is also concerned about issues such as cumulative exposure, the effect of CBD on children, adolescents and pregnant or nursing mothers.
CBD may interact with some prescription medications—specifically those medications that interact with the liver’s detoxification process, particularly with an enzyme known as CYP3A4. If you are taking any prescription medications, talk to your pharmacist about potential interactions with CBD. As a very general rule of thumb, look for warnings against using a medication with grapefruit juice—these medications often also interact with CBD. A partial list of medications that should NOT be taken with CBD includes:
You should always talk to your own healthcare provider when adding CBD—or any other supplement—to your daily routine. The wide use of CBD is recent—and we are still learning a lot about it because there is still a lot we don’t know. Telling your healthcare provider may allow them a better understanding of your health needs and will help them keep track of any side effects or drug interactions.
Overall, CBD is safe for most people to use at the dosage (potency) level most people use. Check the reputation of the company you are buying from, check out their CoAs, talk to your pharmacist and healthcare provider and above all, Start Low and Go Slow when using CBD.