The popular wellness product CBD – short for cannabidiol – is one of a number of compounds known as cannabinoids derived from cannabis and hemp plants. Unlike the most common cannabinoid, THC, CBD won’t get you high – but there is increasing evidence that it can produce therapeutic effects for a range of conditions including pain, anxiety, sleeping disorders and certain cancer symptoms.
If you’re new to using CBD, one of the questions you may be asking is how quickly could it have a positive effect. Below, we’ll explore how different ways of taking CBD can influence this, how long the effects might last and how much you should take, as well as considering the safety and side-effects of CBD.
How long does CBD take to work?
There are two different questions to consider here.
Firstly, there’s how long it takes for CBD to be absorbed into the bloodstream and to thereby begin interacting with the Endocannabinoid System and other receptors that it is thought to influence. This can range from a few minutes to several hours, depending on a number of factors but in particular how you take the CBD.
Secondly, there’s how long it takes before you actually experience any noticeable effects. This may sometimes be measured in days or weeks rather than minutes and hours, depending on the approach you take.
Let’s address these one at a time.
Which is the fastest method of getting CBD into your system?
CBD products come in a variety of forms. Bottled oils contain a CBD solution, usually in a carrier oil such as hemp, olive or coconut, and tend to come with a dropper so you can take measured doses orally or add them to food and drink. There are also e-liquids for vaping, CBD capsules, lozenges and chewable gummy sweets, as well as topical creams that can be applied directly to specific areas of the body.
The speed with which some of these products deliver CBD into your system depends on a range of factors but we can say with some certainty that inhalation via vaping is on average the fastest method. Given the current health concerns around vaping, however, it may not be the safest.
On that basis, CBD oil taken under the tongue – sublingually – is likely your best option, usually reaching the bloodstream within 15 to 30 minutes via the capillary-rich mucous membrane which allows the CBD to bypass the liver and digestive system. Just place the desired amount under your tongue using the dropper, hold it there for a minute or two, then swallow.
You can also choose to swallow CBD oil directly or add it to food and drink. However, the CBD will take longer to be absorbed – generally measured in hours rather than minutes – depending on what you’ve eaten and how long ago.
It’s also worth being aware that when you ingest CBD less of it will eventually reach your bloodstream, as some will be destroyed during digestion. Research suggests that CBD is better absorbed when taken with high-fat foods. There is also some evidence that it can begin to degrade in liquids above 71°F, meaning you may not get as much as you expect from your daily CBD coffee.
How long CBD takes to enter the bloodstream via each method
- CBD vaping liquids – the quickest way to absorb CBD; as fast as 5-15 mins
- CBD oil, taken sublingually – minutes rather than hours; perhaps 15-30 mins
- CBD oil, ingested – may be as fast as 30 mins but generally hours rather than minutes; can vary widely depending on what you’ve eaten and when
- CBD lozenges – there may be a degree of more rapid absorption through the membranes in the mouth before ingestion
- CBD gummies and capsules – similar to ingested oil
- CBD creams – may reach targeted areas more quickly than ingesting CBD; the Arthritis Foundation says effects may be felt within 15 to 45 mins; some evidence suggests they may peak at around 90 mins
How long does CBD take to have an effect?
As outlined above, CBD may reach your bloodstream and begin to interact with various receptors in a matter of minutes or hours, dependent on the method of consumption. However, that may not mean you actually notice any effects of the CBD within that given time period.
There are two main things to consider here.
Firstly, you need to find the right dosage, which can depend on a variety of factors including weight, individual body chemistry and the specific condition you are aiming to treat. For most people, CBD is known to have limited low-level side-effects but, erring on the side of caution, the best way to find your ideal dosage is to start small, perhaps 5-10mg once or twice per day, and work your way up in similar increments until you reach the optimum level without any prohibitive adverse effects.
Secondly, it can sometimes require repeated doses over a number of days or weeks before the full effects of CBD are felt. This may be partly due to the way that CBD can accumulate in the body.
And, of course, while there is good evidence that CBD can help to alleviate symptoms of certain conditions in some people, it is certainly not a panacea and may not work for everyone.
How long do the effects of CBD last?
Just as the time it takes for CBD to take affect can vary dependent on factors such as body mass and the method of consumption, so can the length of time those effects may last.
A 2016 study into different delivery methods of another cannabinoid, THC, showed that effects last between one and four hours when vaping, and in some cases more than six hours after ingestion.
Another study noted the inherent unpredictability of edible products. However, while this may be an issue for those consuming THC with its psychoactive – ‘high’ – effects, given the positive safety profile of cannabidiol it’s no more than a slight inconvenience to CBD users if any beneficial effects begin to wear off sooner than they might ideally like.
How long does CBD stay in your system?
While there may be a cumulative effect of CBD use, meaning that you are likely to gain greater benefits if you take it regularly, some research suggests that even at high dosages it is eliminated from the body relatively quickly after you stop using it.
A 1991 study published in the journal Pharmacology, Biochemistry and Behavior gave patients an oral dose of around 700mg of CBD per day over a six-week period. It found that just one week after the final dose, CBD levels in the blood averaged just 1.5 ng (nanogram – one-billionth of a gram) per ml and were virtually undetectable after that.
A 2018 review of studies looked at the half-life of CBD – the time it takes for the amount in the body to reduce by 50% – and found that it varied greatly depending on the method of consumption.
Continued oral doses of CBD had a half-life of two to five days. But when administered in an oromucosal spray, the half-life was between 1.4 and 10.9 hours. Oromucosal sprays target the permeable mucous membranes in the mouth, specifically the cheeks, so may be comparable to CBD oil taken sublingually, via the membrane under the tongue.
CBD taken by inhalation had a half-life of 31 hours, while given intravenously it was around 24 hours.
So however you take CBD, it appears that it’s likely to be all but undetectable around a week after you stop using it.
Is CBD safe? What are the side-effects?
The popularity of CBD as a natural remedy, and the continued interest in its medical potential, are both in large part due to its low level of significant side-effects. Clinicians generally consider it ‘well tolerated’, meaning it is rare for a subject to drop out of a CBD trial due to adverse effects.
However, if you’re thinking of taking CBD for the first time, it’s certainly worth being aware of the side-effects that some users experience.
A recent review of clinical studies into the effects of CBD on epilepsy and psychotic disorders found that while many patients experienced no side-effects at all, the most common were tiredness, diarrhoea, and changes of appetite/weight.
A study of over 2,400 CBD users published in 2018 determined that dry mouth was the most commonly experienced, noticed by 11% of those surveyed. Other sources suggest CBD oil can sometimes cause nausea and mood changes.
International regulations on the safety of CBD
In recent years, a number of major international law-makers and regulators have updated their guidance around CBD to reflect the general view that it does not pose a health risk to humans.
In a report published in 2017, the World Health Organization said there was no evidence that CBD was addictive or that it posed any public health risks.
In November 2020, the Court of Justice of the European Union ruled that CBD is not a narcotic because “it does not appear to have any psychotropic effect or any harmful effect on human health”. Later that year, the United Nations down-classified cannabis and cannabinoids such as CBD, opening the door for them to be more thoroughly investigated for their medical potential.
While research into CBD is ongoing, however, the UK’s Food Standards Agency advises as a precaution that people in vulnerable groups, such as pregnant and breastfeeding women, do not use CBD and that healthy adults limit their intake to 70mg per day unless advised by a doctor.
It is also important to talk to your doctor if you are on existing medication and are considering taking CBD.
CBD can inhibit the metabolisation of certain drugs, leading to increased levels in the body and potentially greater side-effects. CBD works in a similar way to grapefruit juice, which should not be consumed with some medications, so any drug carrying a grapefruit warning should not be taken with CBD without medical advice.