Hemp has been used for medicinal purposes since around 2300 BC according to Rowan Robinson, author of The Great Book of Hemp: The Complete Guide to the Environmental, Commercial, and Medicinal Uses of the World’s Most Extraordinary Plant.
Additionally, some of the health conditions it has been used to help treat since that time include those related to digestive disorders, neurological issues, insomnia, depression, migraines, and inflammation.
While this is good news for people who suffer from these
types of ailments, supplements made from hemp oil do come with some potential
side effects. Among them are low blood pressure, drowsiness, diarrhea, and dry
1. Low blood pressure
In June 2017, the journal JCI Insight published a randomized
crossover study involving nine healthy male volunteers, each of whom was
given either 600 mg of CBD—which stands for cannabidiol, a derivative of the
hemp plant—or a placebo.
All participants’ cardiovascular data were analyzed both
before and after receiving the active or inactive treatment. Upon analyzing the
numbers at the conclusion of the study, it was found that those who took the
CBD experienced lower resting blood pressures than those who received the
Although this effect may be beneficial for individuals with
high blood pressure, whether due to stress or some other cause, for those with
normal blood pressures, taking a hemp oil supplement could potentially cause
hypotension (low blood pressure).
Clinic advises that this lowered blood pressure can result in dizziness,
fainting, blurred vision, nausea, fatigue, and confusion. And if the blood
pressure drops too much, it could even become life-threatening.
Hemp oil supplements can also sometimes cause drowsiness.
This only makes sense as research has found that they can help improve sleep.
For instance, in the fall of 2016, the Permanente Journal published a case report
involving a 10-year-old girl suffering from sleep-related issues such as
feeling restless, having interrupted sleep, and not being able to sleep alone
after being sexually abused and subsequently diagnosed with post-traumatic
After taking 25 mg CBD oil at bedtime and 6 to 12 mg during
the day, the young girl experienced gradual increases in both sleep quality and
sleep quality. In just five months’ time, she was also able to finally sleep
alone most nights.
After conducting a review of 132 original
studies, German researchers Kerstin Iffland and Franjo Grotenhermen found that
some participants experienced loose bowels after taking CBD. For instance, in
one study involving 137 participants, 17 percent reported diarrhea as a side
effect that occurred after treatment.
However, it should also be noted that this effect was
reported after taking a drug which contained CBD. Therefore, it is unclear
whether it was the CBD itself that caused the diarrhea in these participants or
some other ingredient contained within that particular drug that created this
effect as many of the other CBD studies included in this review did not report
this side effect.
4. Dry mouth
It’s also possible that hemp oil supplementation can lead to
an effect called “dry mouth.” Just like it sounds, dry mouth is a condition in
which the mouth feels dryer than normal and occurs when the level of saliva is
published in Experimental Biology and
Medicine explains that cannabinoids can cause this decreased level of
saliva production due to their effect on the CB1 and CB2 endocannabinoid
receptors found in the glands that are responsible for saliva production.
Additional safety precautions with hemp oil supplements
In addition to these potential side effects, there are also
some instances where it may be unsafe for certain individuals to take a hemp
oil supplement. The first is related to expecting mothers.
Though there have been limited studies in this area, research conducted on
animals has found that maternal exposure to CBD can potentially lead to altered
endocrine function in male offspring. This same study noted that the
concentrations of brain biogenic amines were impacted in these offspring as
Hemp oil supplements may also not be appropriate for individuals
with Parkinson’s disease as one overview of the
research found that some studies have noted a worsening of motor scores in
those exposed to CBD. This overview further stated that other studies have been
inconclusive at best.
Because side effects to any type of supplementation can vary
from person to person, it is always recommended that patients consult with
their primary care physicians before deciding to take a hemp oil supplement.
Also, if any negative side effects are experienced, it may be best to
discontinue use until it can be verified that this supplement is safe for the
individual and his or her physical condition.