CBD is a generally safe substance with few and minor side effects (1). But full-spectrum CBD can possibly make you tired.
Although it depends on many factors, your chances of feeling tired go up with increasing CBD dosages. That’s why research studies using very high doses of pure CBD reported tiredness and sleepiness as possible side effects.
Read on for a more detailed explanation of whether full-spectrum CBD can make you feel fatigued.
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Tiredness and Other Side Effects of CBD
Although cannabidiol (CBD) is very safe, human studies have reported the following side effects: (1)
- Low blood pressure (hypotension)
- Dry mouth
- Changes in appetite or weight
This means that any form of CBD can make you tired. However, these studies used ridiculously high daily doses of pure CBD — anywhere from 200 mg to as high as 50 mg per kg of body weight (equivalent to 4000 mg for someone who weighs 80 kg).
These doses are far beyond what most people use. The average person takes about 20-100 mg of CBD per day, which is much lower.
Besides, the studies mentioned above used pure CBD (isolate), which is different from full-spectrum CBD.
CBD Side Effects: Full Spectrum vs. Isolate
Full-spectrum CBD is less likely to cause side effects than pure CBD because of something researchers call the “entourage effect” — the synergy between the cannabinoids, terpenes, and other active ingredients in cannabis (2).
This was demonstrated by studies conducted on people with epilepsy, where patients using full-spectrum CBD-rich extracts experienced fewer side effects and required smaller doses to achieve relief than people taking pure CBD isolate.
More specifically, 76% of epilepsy patients who used pure CBD reported mild side effects, including tiredness, compared to only 33% for those who took full-spectrum CBD (3).
Similarly, 26% of the study participants who used CBD isolate reported severe side effects, compared to only 7% for full-spectrum CBD users.
On top of that, the patients who used full-spectrum CBD required doses that were, on average, more than four times smaller than people taking pure CBD.
The bottom line is that although any form of CBD can potentially make you tired, full-spectrum CBD is less likely to do so.
How You Take the CBD Also Matters
Another factor that can influence the effects of CBD is how you take it.
For example, when you swallow CBD — as you would with capsules or gummies — it’s poorly absorbed because it has to go through the digestive system and the liver before reaching the bloodstream (4).
Because of this, the effects of oral CBD are weaker than CBD oil. So if you were to take a high dose of CBD oil (60 mg), it would be more likely to make you tired than 60 mg of CBD in a capsule.
On the other hand, vaping CBD offers the highest absorption of any method. So if you use equal doses, vaping CBD is more likely to make you feel tired than other forms of CBD.
If You’re New to CBD, Start Low
While you’re unlikely to get tired from using full-spectrum CBD, it doesn’t hurt to be cautious. Everybody responds differently to CBD for many reasons, such as body weight and genetics.
A dose that might have zero effect on one person could make someone else feel tired. That’s why we always recommend that new CBD users start with a small dose and gradually raise it (5).
For example, you could start with 10 mg, wait two hours to see the effects, and raise the dose again if you didn’t notice any changes.
This method works well because you’ll be able to find the minimal dose that provides the desired effects, so your CBD product will last longer. You’ll also have a lower chance of feeling tired since the likelihood of side effects goes up with the dosage.
- Iffland, Kerstin, and Franjo Grotenhermen. “An update on safety and side effects of cannabidiol: a review of clinical data and relevant animal studies.” Cannabis and cannabinoid research 2.1 (2017): 139-154.
- Russo, Ethan B. “Taming THC: potential cannabis synergy and phytocannabinoid‐terpenoid entourage effects.” British journal of pharmacology 163.7 (2011): 1344-1364.
- Pamplona, Fabricio A., Lorenzo Rolim da Silva, and Ana Carolina Coan. “Potential clinical benefits of CBD-rich cannabis extracts over purified CBD in treatment-resistant epilepsy: observational data meta-analysis.” Frontiers in neurology 9 (2018): 759.
- Huestis, Marilyn A. “Human cannabinoid pharmacokinetics.” Chemistry & biodiversity 4.8 (2007): 1770.
- Lucas, Catherine J., Peter Galettis, and Jennifer Schneider. “The pharmacokinetics and the pharmacodynamics of cannabinoids.” British journal of clinical pharmacology 84.11 (2018): 2477-2482.
Gleb is a freelance writer from Vancouver, Canada specializing in CBD and cannabis. He’s read thousands of studies on CBD and other supplements, helping him translate complex science into plain language. Gleb has tried and reviewed dozens of CBD brands and products, written third-party testing reports, and knows the CBD industry inside and out. When not writing, he likes to kickbox, travel, and tell everyone how awesome intermittent fasting is.