Bioavailability tells you how much of the CBD you take actually reaches your bloodstream and is available for your body to use. This can vary significantly depending on how you take it.
In this article, we look at the key factors that affect bioavailability and share practical tips to help you get the most from your CBD.
When CBD enters the body, much of it can be lost before reaching the blood, especially with methods like swallowing oils or edibles. Digestion and liver processing break down a significant amount.
Only a small portion usually survives to have an effect. For comparison, injecting CBD would give 100% bioavailability, but this is not safe or recommended. (Please note, we do not recommend that you inject CBD under any circumstances.)
Knowing a product’s bioavailability helps you understand how effective it may be. Higher bioavailability means more benefit from a smaller amount.
There are hundreds of different CBD products to choose from, but they are all likely to be used in one of five ways: eaten, inhaled, absorbed under your tongue, inserted rectally or applied to your skin.
Each method transports CBD into your body, but has a different rate of absorption. Different types of products deliver varying percentages of the original measure to your blood. The time it takes for you to feel any effect is likely to be different too.
The most efficient method for CBD absorption is to inhale the vapour using a vaporiser, which can deliver up to 56% of each measure to your bloodstream. This is a significant improvement compared to the 4-20% that is absorbed when you eat CBD.
|
Method used |
Uptake into your bloodstream |
Time to take effect |
|
1. Swallowed / ingested |
4 – 20% |
30 minutes – 2 hours |
|
2. Sublingually (under the tongue) |
~35% |
15 – 25 minutes |
|
3. Rectally |
8 – 50% |
20 – 60 minutes |
|
4. Inhaled or vaporised |
Up to 56% |
10 – 20 minutes |
|
5. Topically (rubbed into skin) |
Can be up to 45% (but localised only). |
25 – 45 minutes |
Any CBD product that is eaten or drunk must pass through your digestive system and your liver. This process has significant waste, which is why only 4-20% of the CBD is available for use in your body.
Although you need to use more significant amounts of CBD to get the effect you want, these products are still popular. Capsules, drinks, and edibles are convenient, discreet and can be flavoured to disguise the taste of the hemp extract.
Holding CBD under your tongue allows it to be absorbed across the thin membrane directly into the blood vessels. This means that it isn't broken down in your digestive system, so a more significant amount is available for use.
This method is most effective with liquid products like oils or tinctures. The desired number of drops is held under your tongue for 1 to 3 minutes and then swallowed. This can result in up to 35% bioavailability, which is significantly better than just swallowing it.
The drawback with this method is that some products are hard to place under your tongue accurately and holding CBD in your mouth can produce an intensely bitter flavour. Finding a product with an accurate dropper or standing in front of a mirror to apply the drops can make it easier to deliver a precise measure. Also, holding oil under your tongue dulls the intensity of the flavour compared to holding it in your mouth as usual.
Because a large number of blood vessels in your rectum are close to the surface, CBD suppositories can have a bioavailability of up to 50%. However, products that can be used in this way aren't easy to find, and most people prefer not to use suppositories if there are other options available.
Vape oils, e-liquids and the dry herb are turned into tiny airborne droplets in a vaporiser. They can then be inhaled, drawing the CBD particles into your lungs. Then they cross the thin mucus membrane into your lung's blood supply.
Your lungs provide a surface area of up to 75 square metres, which makes absorption into your blood quick and easy. The blood that passes through them picks up the CBD, travels to your heart and then around your body before it passes through the liver. This results in a large portion of each inhalation being available for use in your body.
Smoking CBD uses combustion to release particles that can be inhaled. The bioavailability can reach 31%, but you will also be inhaling other by-products (e.g. carcinogens) in the smoke. Also, when hemp or CBD flower burns, some of the cannabinoids are destroyed in the combustion resulting in it being far less efficient than vaping.
Rubbing CBD into your skin is a practical choice when you want to target a specific area, such as a sore joint, a tight muscle, or a patch of irritated skin. Unlike CBD oils or capsules that work systemically, topicals act locally by interacting with cannabinoid receptors in the skin. Because they don’t enter the bloodstream in significant amounts, you won’t feel full-body effects like relaxation or sleepiness.
Instead, topical CBD offers surface-level support. It’s commonly found in creams, balms, or ointments that may also include soothing botanicals like arnica or aloe vera. These blends can help ease tension, calm redness, and support recovery after physical activity.
To get the most out of it, apply it to clean skin and massage it in thoroughly. You may notice a gradual easing of discomfort or tightness, especially with regular use. While results can vary, topical CBD can be a gentle and effective part of your wellness toolkit.
It may come as a surprise, but CBD can stay in your system long after the effects have worn off. How long it remains detectable, its half-life, depends largely on how you take it and how often.
Studies show that inhaled or sublingual CBD tends to leave the body more quickly, while regular oral use allows it to linger much longer. For instance, one review found that oromucosal CBD sprays had a half-life of around 1.5 to 11 hours. In contrast, smoking or vaping CBD resulted in a half-life of about 31 hours, and chronic oral use extended this to between 2 and 5 days.
In other words, a single dose may be mostly cleared within a day or two, but with daily use, CBD can build up and take several days to leave your system. In heavy long-term users, trace amounts of CBD (or its metabolites) have been detected up to 10–14 days after the last dose.
That said, for most casual users, it clears out much faster. One report found that CBD typically remains in the body for anywhere from 26 hours to 5 days. Factors like your dosage, body weight, metabolism and how frequently you use CBD will all play a role. If you use CBD occasionally, it’s likely to leave your system within a couple of days.
To ensure you get the most out of every CBD product, there are some easy ways to boost the amount that reaches your blood. These practical tips involve timing, diet and other natural factors that can influence absorption:
If you’re consuming CBD in a drink, oil, capsule or gummy, hold it in your mouth (under your tongue) for 1 to 3 minutes before swallowing it. This gives some of the CBD a chance to absorb sublingually. For example, biting open a softgel capsule first will release the contents and increase the likelihood they can be absorbed under the tongue.
Gummies or other soft edibles can be chewed thoroughly and then held under your tongue for a bit to improve their bioavailability. This simple step effectively combines oral and sublingual methods, allowing more of the CBD to get into your bloodstream than by just gulping it down.
CBD dissolves well in fats. If you consume CBD along with some dietary fat (or shortly after a hearty, high-fat meal), studies have found that much more of it will survive the journey through your digestive system.
In fact, compared to taking CBD on an empty stomach, a high-fat meal can increase the total amount of CBD absorbed by about four times, and the peak blood CBD level by up to 14 times. This is because fats help carry CBD through the gut wall more efficiently and delay its breakdown.
Have a healthy high-fat snack (such as avocado, nuts, or full-fat yoghurt) when you take your CBD oil or capsules to boost its absorption.
Water-soluble CBD is formulated to mix easily with water and is likely to provide better bioavailability than standard oil-based preparations.
These products use special techniques to create tiny CBD particles or emulsions that can pass quickly across your gut wall and bypass some of the usual digestive breakdown.
Studies have found that the resulting concentration of CBD in your blood is higher with water-soluble formulations than with equivalent oil-based ones, meaning you get more CBD per dose.
In our store, we feature CBD Brothers Purple Edition Plus, a 4% water-soluble CBD/CBDa blend made from Indica-dominant hemp. With 400mg per 10ml bottle, it includes turmeric and terpenes, absorbs easily, and comes with a handy pump for precise dosing—perfect under the tongue or in food and drink.
Our body’s internal state can affect how well we absorb substances. For the best CBD absorption, it helps to be in “rest and digest” mode rather than “fight or flight” mode. When you’re stressed, anxious or rushing around, your sympathetic nervous system is active.
This slows down digestion and sends less blood to your stomach and intestines. As a result, you might not absorb as much CBD (especially if taking it orally) compared to when you’re calm.
In contrast, when you’re relaxed, your parasympathetic nervous system takes over: your heart rate slows, digestion improves, and nutrient absorption increases. Taking a few moments to breathe deeply and settle yourself before using CBD can therefore help your body utilise it more efficiently.
Before taking your CBD dose, try a quick breathing exercise, such as five slow, deep belly breaths, to release any tension in your body. By activating your calming “rest and digest” response, you prime your system to absorb and use CBD optimally.
The time of day you take CBD can influence how you experience its benefits. Some people prefer to use CBD first thing in the morning to promote focus and manage stress throughout the day.
Others find that taking it in the evening or before bed is more effective, especially if they’re using CBD to unwind or support sleep. There isn’t a one-size-fits-all answer – the key is to align your CBD routine with your needs and daily rhythm. Interestingly, research indicates that CBD may have different effects at different times.
For example, one study noted that a high dose of CBD taken in the late afternoon or evening significantly reduced cortisol (the “stress hormone”) levels at night and had a sedative effect. This suggests taking CBD later in the day could be helpful if you tend to feel wired or have trouble sleeping.
On the other hand, a moderate CBD dose in the morning shouldn’t make you drowsy and might help you stay calm and balanced during a busy day. Try this: Experiment with your timing. Try taking CBD at various times – morning, midday, or night – and note how you feel.
You might discover, for example, that a morning dose keeps you clear-headed, or that an evening dose helps you wind down. Once you find the timing that gives you the best results, stick to a consistent schedule for more stable effects.
Your hormonal cycle can subtly affect how CBD works for you. Many women report that it feels more effective at certain times of the month. This is likely due to shifts in hormones like estrogen, which can influence how your endocannabinoid system responds.
For example, during ovulation (when estrogen levels are higher), sensitivity to CBD may increase, making your usual dose feel stronger. In contrast, during the premenstrual phase, when estrogen drops, you might notice higher tolerance or a need for a slightly larger dose.
Every woman is unique, but being aware of these natural fluctuations can be helpful. Try keeping a simple journal of your CBD use, how you feel, and where you are in your cycle. You might find you benefit from a small adjustment in timing or dose on certain days. Listening to your body in this way can help you get the most from your CBD, month after month.
CBD affects each person in a slightly different way but knowing how much of each measure will reach your blood (and how your habits can influence it) will help you make better-informed decisions about what to buy and how to use it.
Vaping or holding CBD under your tongue are generally the most efficient ways to get CBD into your system and, as a result, are likely to be more cost-effective than other methods for many people. Additionally, remember that simple choices like taking CBD with food, finding the right time of day, and keeping yourself relaxed can further enhance its effectiveness.
By choosing a suitable product and pairing it with these smart habits, you’ll give yourself the best chance to get the most out of every drop of CBD.
You might mention negative aspects of vaping too, if any. as usually vaping is linked with many hazardous health issues especially related to lung health.
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A mighty team of natural health researchers led by Daniel Perez Vidal. We follow strict selection criteria and test everything we retail, from ground-breaking food supplements to natural skincare products. Our main area of expertise is CBD.