Side Effects of CBD

Side Effects of CBD

Chapter 4

It’s pretty much all good news when it comes to the side effects of CBD, which, while they exist, are minimal.

In a 2017 overview of clinical data, the International Cannabinoid Research Society reported: “In general, the often described favorable safety profile of CBD in humans was confirmed and extended by the reviewed research.1

Things look even better for CBD when it’s compared to the potential side effects of pharmaceutical drugs used to treat epilepsy and psychotic disorders, some of which have serious side effects. This is particularly important because CBD is being investigated as a potential treatment for psychotic disorders2. It has already been approved to treat some rare forms of epilepsy so its potentially better side effect profile could be welcome news to many who suffer from them3

As reported in the journal, Cannabis Cannabinoid Research:  “In general, the often described favorable safety profile of CBD in humans was confirmed and extended by the reviewed research. The majority of studies were performed for the treatment of epilepsy and psychotic disorders...In comparison with other drugs, used for the treatment of these medical conditions, CBD has a better side effect profile. This could improve patients' compliance and adherence to treatment.4

List of Side Effects

All of this is not to say there are no side effects.  The most commonly reported ones are5:

  •     Tiredness (the state of wishing for sleep or rest) 
  •     Diarrhea (loose bowels)
  •     Changes in appetite (either reduced/increased desire to eat)
  •     Changes in weight (either weight gain or weight loss)
  •     Anxiety (feeling of apprehension or fear)
  •     Irritability (moodiness, most often marked by anger or frustration)
  •     Dizziness/Lightheadedness (feeling faint or unsteady)
  •     Nausea/Vomiting (feeling sick with inclination to vomit or vomiting)
  •     Dry mouth (sticky, dry feeling in mouth)

 Interestingly, the cause of dry mouth, long known to users of cannabis as “cottonmouth,” was uncovered in a study that showed human salivary glands contain cannabinoid receptors. It turns out that CBD actually impedes the secretion of saliva when it interacts with the endocannabinoid system. Hence, dry mouth6.

Studies that have shown what effects CBD does not cause are also encouraging, indicating that it’s “catalepsy is not induced and physiological parameters are not altered (heart rate, blood pressure, and body temperature). Moreover, psychological and psychomotor functions are not adversely affected. The same holds true for gastrointestinal transit, food intake, and absence of toxicity for nontransformed cells.7

In simple English, this means CBD has been found to be non-toxic, doesn’t affect the basic bodily functions of heart rate, blood pressure, and body temperature has no effect on digestion and does not alter psychomotor or psychological functions.



The biggest cause for concern is CBD is potential interaction with other medication. CBD may reduce or even increase the efficacy of other medications that are taken, so an adjustment to the dosage may be required (7).

 This is extremely important and should be a major cause of concern for those on prescription meds because the particular liver enzyme that is inhibited, P450, plays a major role in metabolizing medicine. Interactions with warfarin (for blood clots), antidepressants, antiepileptic drugs, and statins (for lowering cholesterol) often involve these P450 enzymes8. If you are on any pharmaceuticals, you need to consult with your doctor before you start taking CBD.   

Other early tests also indicate CBD may decrease fertilization capacity. So if you are trying to get pregnant (or get someone pregnant), best to consult with a physician before taking it9.

Last, because there is a lack of data on the safety of taking CBD while pregnant or breastfeeding, women who are should err on the side of safety and refrain from taking it until they are no longer pregnant or breastfeeding. 

While CBD is overall safe for consumption with generally mild side effects, there is still a lot more to uncover (such as whether CBD affects hormones) and more long-term studies of greater numbers of participants need to be conducted.

The smartest thing you can do if you’re considering trying CBD oil is to make an appointment with your doctor to review the potential side effects and, most importantly, go over the medicines you’re taking that could be contraindicated by CBD.

Also, if you do start taking CBD, be sure to take time to notice your body’s reactions. It’s a good idea to jot down how you are feeling a week before you start taking CBD and then track any changes afterward. Be especially mindful of the possible side effects listed above, the most common of which are tiredness, diarrhea, and changes in appetite or weight. This will help you get a handle on which effects, if any, might be related to the CBD. 

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