Do you have a condition that you have heard may be helped with cannabidiol (CBD) oil and you are ready to give it a try?
Whether you are suffering from anxiety, mood disorders, headaches, migraines, insomnia, chronic pain, epilepsy, schizophrenia, loss of appetite, multiple sclerosis, or a multitude of other disorders, you are likely wondering how much to take and what kind of product to use.
Luckily, there have been numerous studies that can help to narrow it down and provide some preliminary guidelines while we wait for scientists and doctors to develop more defined dosage standards.
In this article we will review what CBD dosages have been used in human studies and what results and side effects were observed. We will also bring light to where there are holes in the research leaving consumers without specific dosage guidelines to follow.
Table of Contents
While some conditions have been researched with CBD only treatment, many studies that have been conducted are on a combination of THC and CBD.
THC is the psychoactive cannabinoid found in the Cannabis sativa plant, while CBD is a cannabinoid in the same plant without the mind-altering effects.
With research into CBD being relatively recent, there is still much more research needed to provide specific guidelines for conditions.
Here we will review what specific studies have used and the results that were found, which can be used as a guide on where to begin if you would like to try CBD products.
CBD supplementation and its effect on anxiety disorders are one of the more widely studied areas when it comes to how CBD effects those with specific health conditions. Most of these studies have been on animals, so here we will only review the few studies conducted thus far on humans.
CBD has been shown to counteract some of the negative effects of THC, including THC-induced anxiety.
In a 1974 study published in the European Journal of Pharmacology, researchers set out to examine how individuals would respond to THC only, CBD only, or a combination of THC to CBD. 
Subjects were split into 8 experimental groups: placebo, 30 mg THC, 15, 30 or 60 mg CBD, or mixtures of 30 mg THC with either 15, 30 or 60 mg of CBD.
It was found that 30 mg of THC produced anxiety symptoms along with increased pulse rate, psychological reactions, and inhibited ability at time tasks while 15-60 mg of CBD did not lead to these effects.
15-60 mg of CBD was found to block most of the effects of 30 mg of THC, including decreasing the anxiety experienced by participants from the THC.
A 2011 study published in Neuropsychopharmacology set out to see if there was an effect of CBD oil on public speaking induced anxiety.
24 patients with generalized social anxiety disorder were split into two groups: one placebo group and one 600 mg CBD group. Before the simulated public speaking test, these groups took their placebo or CBD 90 minutes prior to the test.
Multiple measures for anxiety were taken at 6 points during the test, including heart rate, blood pressure, and skin conductance, along with a number of subjective ratings based on the Negative Self-Statement scale and the Visual Analogue Mood Scale.
It was found that 600 mg of CBD 90 minutes before the simulated public speaking test led to subjects were experienced significantly fewer anxiety results as compared with a placebo group.
Currently there are no human studies examining the effect of CBD only on PTSD, however there have been multiple case reports that support the use of the whole Cannabis sativa plant for those who suffer from PTSD. , 
One retrospective study was conducted in 2014 and published in the Journal of Psychoactive Drugswith the purpose of analyzing psychometric data on PTSD symptoms that were collected during psychiatric evaluation of patients who applied to the New Mexico Medical Cannabis Program from 2009 to 2011. 
80 patients were evaluated using the Clinician Administered Posttraumatic Scale for DSM-IV (CAPS). Researchers found that patients who used cannabis experienced a 75% greater reduction in CAPS symptom scores when compared to when they were not using cannabis.
The THC:CBD ratio of these patients is not known. More research needs to be conducted on CBD only to provide patients with answers to the questions of what effect CBD only has on PTSD symptoms and in what quantity.
In a 2004 study published in Neuropsychopharmacology 10 healthy male volunteers were tested for subjective fear response using the Visual Analogue Mood Scale. 
One week subjects were given a placebo 90 minutes before the test and the other week they were given 400 mg of CBD before the test. Researchers found that 400 mg of CBD significantly decreased subjective anxiety and increased mental sedation when compared to placebo.
A 2013 study published in Psychopharmacology (Berl) took 48 healthy participants and subjected them to a Pavlovian fear-conditioning paradigm in order to research the effects of CBD on extinction and consolidation of fear memories. 
In this double-blind, placebo-controlled study, researchers concluded that 32 mg of inhaled CBD prior to or after extinction training of fear memories led to a significant reduction in expectancy of shock during reinstatement.
The researchers concluded that CBD may enhance extinction of fear memories in humans, which may help those suffering from a variety of anxiety disorders.
While there is plenty of current evidence supporting the benefit of whole plant Cannabis sativa on headache disorders, human studies examining the effect of CBD only are lacking.
Later we will review some of the studies on CBD and its ability to treat nausea, muscle spasticity, and neuropathic/chronic pain and the dosages used in these studies. Headache disorders share some of these same pathologies, so until there is more research, these studies are the best data available in using CBD only to treat pain.
A very recent study presented at the 3rd Congress of the European Academy of Neurology in Amsterdam in June 2017 examined the effect of a THC-CBD combination in comparison to common medications for migraine headaches and cluster headaches. 
79 chronic migraine sufferers and 48 cluster headache patients were assigned either 200 mg of an oral THC-CBD combination or amitriptyline (migraine patients) or verapamil (cluster headache patients) daily for three months.
The THC-CBD migraine patients experienced a significant reduction in migraine attacks on par with the reduction for those taking the amitriptyline, however for cluster headache sufferers the reduction in attacks was much less.
When the results were examined in more detail, it was found that those with cluster headaches who suffered from migraines as children experienced a greater reduction in their cluster headache pain intensity.
In a 1981 research paper published in The Journal of Clinical Pharmacology, a number of clinical trials performed prior from 1972 to 1981 were examined. 
In one study, 15 insomniac volunteers were given 40, 80, and 160 mg of cannabidiol, 5 mg nitrazepam, and placebo.
Subjects who received 160 mg CBD reported having slept significantly more when compared to placebo, with subjects receiving 40, 80, and 160 mg CBD reporting less dream recall.
Cannabis sativa and its constituents are being researched for the pain and difficulties eating that often accompany cancer patients.
A study published in 2006 in the Journal of Clinical Oncology compared the effects of orally administered cannabis extract composed of 2.5 mg THC and 1 mg CBD, 2.5 mg THC, or placebo orally twice per day for 6 weeks on appetite and quality of life (QOL) in patients with cancer-related anorexia-cachexia syndrome (CACS). 
Increased appetite was found in 73% of those in the THC+CBD group, 58% of the THC group, and 69% of the placebo group, however these differences were not significant.
No significant difference was found between the three groups in relation to appetite, QOL, or cannabinoid-related toxicity. Because of insufficient differences between the groups, and independent data review board recommended to terminate recruitment.
In a high quality study (multicenter, double-blind, randomized, placebo-controlled, parallel-group) published in 2010 in the Journal of Pain and Symptom Management, 177 cancer patients who were experiencing pain were given either CBD+THC, THC alone, or placebo for two weeks in order to study the effect of these compounds on pain relief in cancer patients.
The treatments were given as oromucosal sublingual drops where the THC and CBD are able to be absorbed inside the mouth. The doses for CBD were 20-30 mg/day and THC 22-32 mg/day.
The findings were that the combination of CBD and THC was significantly more effective at decreasing pain when compared to the placebo on the neurological rating scale (NRS), while THC alone showed a reduction that was not significant.
It is important to note that the CBD+THC increased vomiting and nausea on the QLQ-C30 subscore, but not on the NRS, when compared to the placebo.
The vast majority of research that supports the use of CBD for chronic pain relief is with a combination of THC and CBD and is almost always tailored for a specific condition, such as cancer pain, multiple sclerosis pain, and rheumatoid arthritis.
The dosage given in studies varies based on the condition, so it is best to reference back to your specific condition to determine what kind of dosage to try for specific conditions.
Human studies on pain relief tend to be with a combination of both CBD and THC, although this does not mean that taking just CBD would not be effective, there just are not studies to direct us to the efficacy and dosage.
A 2005 study published in Rheumatology set out to determine the efficacy, tolerability and safety of an oromucosal spray medicine named Sativex that is a combination of THC:CBD in a 1:1 ratio. , 
In a double-blind, randomized, parallel group study of 58 patients over 5 weeks of treatments, it was found that, in comparison to placebo, Sativex produced significant improvements in pain at rest, pain during movement, quality of sleep, and multiple measures of pain at present. There was no significant difference in morning stiffness.
Side effects were mild to moderate, with no withdrawal or serious adverse effects found.
Preclinical and clinical trials have shown CBD to have anticonvulsant properties, demonstrating promise for the treatment of seizures. It is important to keep in mind that there are limited human clinical trials and the mechanism of action is not fully understood. 
In a 1981 research paper published in The Journal of Clinical Pharmacology, a number of clinical trials performed prior from 1972 to 1981 were examined, one being on CBD and epilepsy symptoms. 
Fifteen patients were given either a placebo or 200 to 300 mg oral cannabidiol daily for up to 4.5 months. Of the 8 epilepsy patients taking CBD, 7 reported improvement in their symptoms, whereas only one of seven placebo patients reported improvement.
There have been conflicting findings with regards to CBD and its antipsychotic abilities, with some studies finding a reduction in symptoms and others finding no change.1 More clinical studies need to be completed to determine if CBD does help, and if so, how much should be taken.
Here we review the human randomized, double-blind clinical trial that did find improvement in symptoms as a guide for possible effective quantities of CBD for those suffering from schizophrenia.
In a 2009 study published in European Psychiatry, 42 patients with acute schizophrenia were split into two groups: 600 mg oral CBD or amisulpride (an antipsychotic medicine).
Researchers found that CBD and amisulpride equally reduced psychotic symptoms following 4 weeks of treatment. 
Since this study, multiple clinical trials with schizophrenic patients have been initiated, but so far the data have not been published and peer reviewed, so more data on CBD for schizophrenia is on the way. 
In studies that have found a positive effect of Cannabis sativa on pain associated with MS, it has been with a combination of THC and CBD. Similar to schizophrenia studies, there have been conflicting results found in regards to cannabinoids in the treatment of MS symptoms and pain
Here we will review a long-term clinical trial that found efficacy in treating one type of pain associated with MS.
Sativex ® is an oromucosal spray containing a roughly 1:1 ratio of THC:CBD.
In a 2007 clinical trial published in Clinical Therapeutics, an initial 5 week randomized placebo controlled trial of 64 patients examined the effectiveness of Sativex ® in reducing central neuropathic pain in MS patients. The patients in the Sativex ® group used an oral spray containing 2.7 mg THC and 2.5 mg CBD for 5 weeks.
The NRS-11 pain scores in the final week were 3.8 in the Sativex ® group and 5.0 in the placebo group.  The researchers concluded that the cannabis spray was more effective than the placebo in reducing pain as well as sleep disorders in MS patients with neuropathic pain.
Following this trial, an optional indefinite-duration extension was conducted to measure the number, frequency, and type of adverse events (AE) reported by Sativex ® patients.
28 of the patients completed a 2-year follow up. 92% of patients experienced 1 or more AE, with the most common AEs being nausea, dizziness, and feelings of intoxication. The majority of the AEs were mild to moderate.
As with any supplement or product, CBD oil is likely to impact every person differently.
Take alcohol, for example: we all have that friend who can seemingly drink alcohol as if it were water, and another friend who struggles after just one or two drinks. Even caffeine can have drastically different effect on different individuals that varies based on sex, age, and genetic factors.
If that’s not enough, there are so many ways to take CBD! You can smoke it, take capsules, CBD oil, CBD water, tinctures, and creams, and the list goes on.
How you take CBD can have a dramatic difference in how it affects you.
The bioavailability of smoked CBD in humans was found to be much higher than that or oral CBD, which was found to be roughly 31% and 6%, respectively.1 The bioavailability of oral CBD was found to increase with the consumption of food.
Most studies on CBD alone have been through oral administration, however that does not mean that another form would not work well, just that there are not yet studies to help provide guidance.
If you decide to try CBD for a personal health condition, remember to use the scientific studies outline above as a guide, but to listen to your body.
It is best to start at a low dosage and slowly increase until you find the quantity that helps relieve your symptoms without taking more than you need.
Try different forms and see what one you are most comfortable with. If taking orally, take with food to increase the bioavailability.
Additionally, cannabinoids are biphasic, meaning that they may produce opposite effects at low versus high doses. Keep this in mind as you monitor your response.
Tinctures of CBD oil are one of the most popular ways to take CBD.
When you take a tincture of CBD, place the oil under your tongue to allow it to be absorbed in your mouth before swallowing. This helps to increase how much your body absorbs.
Also take the tincture with food as studies have shown this to increase the bioavailability of the CBD. 
With herbs and supplements it is important to remember that they are not strictly regulated by the U.S. Food and Drug Administration. This means that the strength and other aspects of a product can vary widely.
If you start low and increase slowly, you are unlikely to experience dramatic side effects. That said, side effects do exist.
Multiple studies have found mental sedation effects of orally administered CBD, although these findings were often at high dosages, from 300 to 600 mg/day CBD.1 Other studies at similar dosages did not find any sedation effects, so monitor your personal response.
As discussed earlier, the 2-year study of those taking Sativex ®, containing both THC and CBD, was found to lead to mostly mild to moderate adverse effects, such as nausea, dizziness, and feelings of intoxication, however these effects could be due to THC, CBD, or both. 
Additionally, CBD may interfere with some medications, so check with your doctor if you are taking any medications currently. 
Overall, it has been found that high doses of up to 1,500 mg/day and chronic use of CBD is well tolerated. 
We will end with steps to take when adding CBD into your supplement routine.
Speak with your doctor about any herbs and supplements that you add into your diet, particularly if you take any prescription medications.
As research on CBD is still in its infancy, more studies need to be conducted to discover possible pharmacokinetic interactions as well as more standardized dosage guidelines.
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