The study found that among the 65% of people taking cannabis for pain, 80% found it was very or extremely helpful.
This led to 82% of these people being able to reduce, or stop taking over the counter pain medications, and 88% being able to stop taking opioid painkillers.
74% of the 1,000 interviewees bought it to help them sleep - 84% of whom said the marijuana had helped them, and over 83% said that they had since reduced or stopped taking over-the-counter or prescription sleep aids.
The study suggests that cannabis could lower opioid use. However, the researchers caution that more needs to be done to understand the potential therapeutic benefits of cannabis.
"Approximately 20% of American adults suffer from chronic pain, and one in three adults do not get enough sleep," says Dr Gwen Wurm, Assistant Professor of Clinical Pediatrics at the University of Miami Miller School of Medicine.
Traditional over the counter medications and painkillers can help, however they may have serious side effects. Opioids depress the respiratory system, meaning that overdoses may be fatal.
"People develop tolerance to opioids, which means that they require higher doses to achieve the same effect," says Dr. Julia Arnsten, Professor of Medicine at Albert Einstein College of Medicine. "This means that chronic pain patients often increase their dose of opioid medications over time, which in turn increases their risk of overdose."
Although less common, sleeping pills can lead to dependence, and can also cause grogginess the next day, interfering with people's work and social lives.
As a consequence, some people are looking to marijuana to help with their symptoms.
To find out more about these users, Wurm and her colleagues used survey data from people who purchased cannabis from two retail stores in Colorado, US, where it is legal for both medical and recreational use - meaning any adult over 21 with a valid government ID may purchase product.
"In states where adult use of cannabis is legal, our research suggests that many individuals bypass the medical cannabis route (which requires registering with the state) and are instead opting for the privacy of a legal adult use dispensary," says Wurm.
Although the survey was conducted among customers willing to participate - meaning the results may not reflect the overall population of dispensary customers - other national survey data, and data from medical patients at medical cannabis dispensaries, also demonstrate that people who use cannabis to treat symptoms both decrease and stop their use of prescription medications.
The study adds weight to the theory that widening access to medical cannabis could lower the use of prescription painkillers, allowing more people to manage and treat their pain without relying on opioid prescription drugs that have dangerous side effects.
This is backed up with other research that shows that states with medical cannabis laws have a 6.38% lower rate of opioid prescribing, and that Colorado's adult-use cannabis law is associated with a relative reduction in opioid overdose death rate from 1999 to 2010.
Wurm adds: "Nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen cause GI bleeding or kidney damage with chronic use. Paracetemol (Acetaminophen) toxicity is the second most common cause of liver transplantation worldwide, and is responsible for 56,000 ER visits, 2600 hospitalizations, and 500 deaths per year in the U.S."
However, the researchers caution that more research is needed to understand the health benefits and side effects of cannabis.
"The challenge is that health providers are far behind in knowing which cannabis products work and which do not. Until there is more research into which cannabis products work for which symptoms, patients will do their own "trial and error," experiments, getting advice from friends, social media and dispensary employees," says Wurm.