By Roger Chriss, PNN Columnist

Medical cannabis continues to thrive. Older Americans are flocking to cannabis dispensaries and more states are considering legalization or adding approved indications.

But there is relatively little information about the potential risks and pitfalls of medical cannabis. The New York Times reports that “researchers are uneasy about the fact that older people essentially are undertaking self-treatment, with scant guidance from medical professionals."

There are three broad categories of precautions that people who are using or considering medical cannabis should be aware of.

Product Quality and Reliability

Reliably sourcing a high-quality cannabis product can be difficult. Product labels are often inaccurate. A 2015 survey of cannabis edibles in Seattle, San Francisco and Los Angeles found that only 13 of the 75 products tested (17%) had labels that accurately indicated their THC content.

More recent testing in California found that about a quarter of the cannabis-infused cookies, candies and tinctures failed safety tests because of improper labeling or because they contained pesticides.

One lab in Sacramento was even found to be falsifying test results. A spokesman for the California Cannabis Industry Association said it's an open secret in the industry that companies have been paying for favorable test results.  

States from Massachusetts to Nevada are also seeing problems with pesticides, mold and heavy metals contaminating medical-grade cannabis.

Interactions and Contraindications

Cannabis consists of over 100 cannabinoids, as well as other physiologically active substances. This makes for a lot of possible drug interactions. Drugs.com lists 129 major and 483 moderate interactions that cannabis can have with medications such as acetaminophen, codeine, fentanyl, hydrocodone, pregabalin and oxycodone.

Moreover, cannabis has been found to reduce thyroid stimulating hormone (TSH) levels. For people with thyroid disease, artificially suppressed TSH can affect medication decisions. Similarly, cannabis reduces platelet aggregation, a problematic and even risky issue for people with bleeding disorders or low platelet counts.

A new review in Current Opinion in Neurology found that cannabis exacerbates tinnitus (ringing of the ears), a common problem for older people and people with Meniere’s disease or Charcot-Marie-Tooth disease.

Tolerance and Withdrawal

Cannabis tolerance may be a clinically significant issue. A new study on CBD oil for seizure management found that cannabidiol loses its effectiveness in treating epilepsy. About one-third of patients in the study stopped taking CBD because of a lack of benefits or side effects like sleepiness and gastrointestinal trouble.

“CBD is a good option for children and adults with certain kinds of epilepsy, but as with anti-epileptic drugs (AEDs), it can become less effective over time and the dose may need to be increased to manage the seizures,” said lead author Shimrit Uliel-Sibony, MD, head of the pediatric epilepsy service at Tel Aviv Sourasky Medical Center.

Also important is withdrawal. Recent research on cannabis withdrawal in a group of chronic pain patients found that about two-thirds reported at least one moderate or severe withdrawal symptom. Withdrawal symptoms included sleep difficulties, anxiety, irritability and appetite disturbance.

In sum, there are important issues to address when using or considering medical cannabis. Unfortunately, knowledgeable physicians are hard to find and high-quality cannabis is difficult to obtain reliably. It is hoped that this will change soon so that medical cannabis can be used safely and effectively.

Roger Chriss lives with Ehlers Danlos syndrome and is a proud member of the Ehlers-Danlos Society. Roger is a technical consultant in Washington state, where he specializes in mathematics and research.

The information in this column should not be considered as professional medical advice, diagnosis or treatment. It is for informational purposes only and represents the author’s opinions alone. It does not inherently express or reflect the views, opinions and/or positions of Pain News Network.