Cannabidiol (CBD) oil for flu and common cold symptoms is not a new remedy. Yet how does it help and what will it really work for, according to research? Also, how should one use it for optimal effect?
Currently, there are no traceable scientific data on using CBD oil for flu or the common cold, meaning that apparently little to no research for these indications has been done so far.
Yet the available data on CBD's ability to address inflammation—as well as bacterial and even viral infection—is promising.
So, based on these, we can tentatively say that with CBD oil, common cold and flu symptoms could very well meet their nemesis. It could also perhaps fight off microbes such as bacteria and viruses.
Let's look at what science says so far.
Sometimes the body's own immune response can cause problems, even serious ones. Herbal remedies, such as CBD, have been shown to ameliorate this response.
The inflammatory response is part of the immune system's way to fight pathogenic invaders (such as the flu virus and bacterial infections) and other diseases.
Yet as explained in a ScienceDirect article:
"Sometimes, however, inflammation itself becomes so intense that it becomes part of the problem, and herbal remedies can be used to provide some measure of relief without full suppression.
This can help to further facilitate the healing process, allowing the body to respond normally but without undue suffering or damage to the patient." 
CBD is a known anti-inflammatory remedy.
Colds and flu are both associated with inflammatory symptoms, such as painful limbs and joints. CBD could help with this.
Its ability to fight inflammation in the body is one of CBD's most promising therapeutic uses. It has been tested extensively, especially in animals, to treat inflammation of the joints and bowels—with excellent results.
For instance, in a 2004 study on rats with induced inflammation of the paw, the researchers found that "... oral cannabidiol has a beneficial action on two symptoms of established inflammation: edema and hyperalgesia." 
Edema is swelling of the tissue due to water retention, and hyperalgesia is great sensitivity to pain.
So, this study demonstrates CBD's efficacy to help with these symptoms, which may be why many swear by a CBD-infused balm or taking CBD oil drops when they feel achy because of an infection.
Cannabis, in general, has been shown to have antiviral and antibacterial properties.
As one review concluded:
"There is a large body of evidence from in vivo and in vitro models showing that cannabinoids and their receptors influence the immune system, viral pathogenesis, and viral replication." 
This means that cannabinoids, including CBD, seem to demonstrate the ability to kill viruses and viral replication.
Another lab study confirmed CBD's antimicrobial ability, even if the exact mechanism is unclear. The researchers also found the following:
"The potent activity against strains possessing the NorA and TetK efflux transporters suggests that cannabinoids are not substrates for the most common resistance mechanisms to current antibacterial agents, making them attractive antibacterial leads."
This means that cannabinoids appear to discourage drug or treatment resistance in bacteria. 
Another study on Wistar rats demonstrated CBD's immunosuppressive (anti-inflammatory) action as well as its ability to increase cells that fight viruses:
"... [A]dministration of cannabidiol at a dose of 2.5 mg/kg increased the total and percentage NKT cells numbers, and the percentage number of NK cells. The results suggest that repeated treatment with cannabidiol inhibits specific immunity by reduction of T, B, T cytotoxic, and T helper cell numbers, and may enhance nonspecific antiviral and antitumor immune response related to NK and NKT cells." 
NK and NKT cells are some of the immune system's "fighter cells" that combat not only viruses but also tumors.
However, these studies are largely preliminary, and many were conducted in laboratory petri dishes or on animals.
This means that the research is still inconclusive, as mentioned, and needs to be tested in clinical models (on a human population, that is).
That said, CBD is largely considered safe for use, even in high doses. One can, therefore, experiment without fear of complications.
Following are a few things to keep in mind when considering CBD oil or cannabis next time the flu or cold strikes. Fortunately, hemp-derived CBD oil is now 100 percent legal everywhere in the U.S.A. and readily available online.
This means of ingesting cannabinoids is unlikely to be good for the lungs or the best way to get in a good dose of CBD. The smoke could irritate an already raw throat and inflamed lungs. Also, getting high while having a fever could be a very unpleasant experience.
Pure CBD oil is not useless, but it has certain limitations. For instance, the dose needs to be just right, or the oil will not have an effect. Practically speaking, it means that if a person takes too little or too much, there will be little to no noticeable benefit.
Full-spectrum CBD oil, on the other hand, has well-known advantages over pure CBD or CBD isolate. The main advantage is that it seems to work better together with other cannabinoids and terpenes found in hemp, and higher doses have enhanced effects.
Like with most things in life, quality oil is more likely to give better results.
RELATED: How To Choose A High-Quality CBD Oil
Soon, hemp CBD oil for flu could prove to be preferable over many other medicines.