Using herbal cannabis for joint and bone pain is likely to have more risks than benefits, according to a new review of studies.
What do we know already?
People with rheumatic diseases – like osteoarthritis, fibromyalgia, and rheumatoid arthritis – often live with long-term joint pain. There are painkillers available, but some people find that these treatments don’t reduce their pain enough for them to be able to live a normal life, or that they have unwanted side effects. This means there are a lot of people who may need other ways to manage their pain.
Previous studies in the UK and Australia have found that about one-third of people who have rheumatic pain said they had used cannabis to treat their bone and joint pain. Cannabis is an illegal drug in the UK but it has been approved and is legal for “medicinal use” in some parts of the United States. This is because two substances found in the cannabis plant, tetra-hydro-cannabinol (THC) and cannabidiol, have pain-relieving properties.
But using herbal cannabis carries long-term health risks. It can cause lung problems (if smoked), an irregular heartbeat, and dangerously low blood pressure. Long-term cannabis use can also increase the risk of a heart attack and has been linked to mental illness and dependence.
Most of what we know about the health risks of cannabis comes from studies in younger people who are usually in reasonably good health. It’s a concern that the health risks may be worse in people with rheumatoid diseases, who are generally older and may have other health problems. The health risks of cannabis may also be worse if it is used for a long time, which it is likely to be if a person has a long-term illness.
So we know that people are using herbal cannabis to treat rheumatic pain, and we know there are risks. But we don’t know whether it works. To try to find out, in this review, researchers took an overview of all the published studies of cannabis in people with rheumatic pain.
What does the new study say?
The researchers’ main findings were:
- Studies of people with rheumatoid arthritis and fibromyalgia have been too small to give clear results. So far there is no good evidence that herbal cannabis helps with pain caused by these conditions.
- There’s some evidence that cannabis can help with cancer pain and pain affecting the nerves ( neuropathic pain). But the causes of cancer pain and neuropathic pain are very different from the causes of rheumatoid pain. We can’t assume that because cannabis helps pain caused by some types of long-term illness, it would help rheumatoid pain.
- There’s no way to know how much of the pain-relieving compounds end up in the blood when a person smokes or ingests cannabis. The strength of cannabis can vary a lot and how much ends up in the blood can depend on how it is consumed.
How reliable is the research?
This was a comprehensive review of the literature to explore what we know about cannabis for rheumatic pain. It should be a reliable study. But the researchers point to the need for more good-quality research.
What does this mean for me?
The only cannabis-related treatment that is legal and approved for medicinal use in the UK is called cannabis extract (the brand name is Sativex). It is used to treat muscle spasms in people with multiple sclerosis, and is usually prescribed by specialist doctors. For any other medical condition, cannabis is not recommended and is illegal. This review suggests that people with rheumatic diseases shouldn’t use herbal cannabis as an alternative treatment for pain, as it is unlikely to help and it may cause harm.
