Medical cannabis has a wide range of therapeutic applications. It can relieve pain [1] and cramps [2], reduce migraine symptoms [3], alleviate sleep disorders [4], counteract nausea [5], stimulate appetite [6], and have an anxiety-reducing effect [7]. When used properly, it has comparatively mild side effects [8]. Nevertheless, cannabis-based treatments also require careful coordination with other therapeutic measures, medications, and the patient’s health condition. In this article, you will learn which contraindications may prevent treatment with medical cannabis and which precautions should be considered when undergoing cannabis therapy.
What Are Contraindications?
Contraindications are factors that argue against the medical use of a drug or a form of therapy. Since they can pose potential risks to patients, they must be carefully evaluated. This includes drug interactions with medical cannabis, but pre-existing conditions and their possible side effects also play a role.
In other words, not every therapy is suitable for every person, making an individual assessment necessary. Examining potential contraindications is mandatory in medical practice, as it helps to determine an appropriate treatment approach and ensure patient well-being. This requires close coordination between treating physicians and patients so that an informed decision can be made regarding the appropriate form of treatment.
Who Should Be Cautious When Using Medical Cannabis?
Since medical cannabis is prescribed under medical supervision, with dosage gradually adjusted to meet the needs of patients, the risk of side effects can be effectively minimized [9]. When used correctly, it is a relatively mild medication, making it well-tolerated by many patients. However, there are several contraindications where cannabis therapy could present disadvantages.
Severe Mental Illness
For individuals with severe mental illness, including psychosis, schizophrenia, and dissociative identity disorder, THC containing compounds are generally unsuitable due to the psychoactive effects of tetrahydrocannabinol (THC). In those with pre-existing conditions, it may trigger symptoms or, in some cases, even intensify them [10].
Heart Diseases
Since the immediate effects of cannabis, particularly THC, can stimulate the cardiovascular system, caution is advised for individuals with heart disease. Cannabis can also increase blood pressure and heart rate, which may pose additional risks for an already strained heart. Depending on the specific condition, it must be assessed on an individual basis whether cannabis therapy is still appropriate [11].
Lung Diseases
Lung diseases, such as asthma, do not fundamentally rule out cannabis therapy. However, relevant studies that highlight potential risks primarily focus on smoking cannabis [12], as it is known to place stress on the airways. In other words, potential risks are often linked to the method of consumption, meaning that therapeutic inhalation should be carefully considered.
Inhalation and Alternative Methods
However, inhaling cannabis preparations using a vaporizer can cause side effects in individuals with lung damage. In such cases, oral or sublingual cannabis preparations, such as cannabis oils, may offer a possible alternative. Nonetheless, since specific concerns cannot be ruled out in individual cases, consulting knowledgeable physicians is strongly recommended to ensure a safe and personalized therapy.
Pregnancy and Breastfeeding Mothers
The exact effects of cannabis consumption during pregnancy remain unknown. However, there are indications of potential consequences for the unborn child and the course of pregnancy, as some studies suggest developmental and attention disorders, psychological abnormalities, and increased stress sensitivity. In other words, cannabis use could pose potential risks for both mother and child, making careful consideration necessary.
Increased Risk of Hypertension and Preeclampsia
These concerns, however, do not specifically refer to the therapeutic use of medical cannabis preparations [13]. Nevertheless, during pregnancy, cannabis may increase the likelihood of high blood pressure, as certain components could affect the cardiovascular system. Some studies also indicate a heightened risk of preeclampsia [14]. In other words, the effects of cannabis during pregnancy are not yet fully understood, which is why pregnant women are advised against cannabis treatment for safety reasons.
Since THC from cannabis preparations is fat-soluble and can be stored in the body, it is transferred into breast milk. However, the long-term effects on the infant have not been sufficiently researched. In other words, further studies are needed, meaning that cannabis therapy is currently not recommended for breastfeeding mothers [15].
Addictive Behavior
In a medical cannabis therapy, the risk of dependency can be minimized. However, individuals with a history of substance use disorders are at a higher risk of developing an addiction, as previous addiction problems can increase the likelihood of relapse.
Therefore, an individual’s medical history plays a crucial role, and in such cases, cannabis therapy is often discouraged [16].
Drug Interactions with Medical Cannabis
So far, only a few negative interactions between medical cannabis and other medications are known. However, these cases must be carefully considered, as they can impact the safety and effectiveness of treatment. Therefore, a well-structured therapy plan is essential.
Known Interactions
Cannabis affects several CYP enzymes in the liver. Since these enzymes are responsible for metabolizing many medications, cannabis can, depending on the dosage, improperly enhance their effects [17]. However, not all medications are equally affected. For example, anticoagulants such as warfarin or phenprocoumon may pose an increased risk of bleeding due to the inhibited breakdown of active ingredients [18].
Narcotic and sedative medications, including some sleep aids, may also have stronger effects under the influence of cannabis, increasing the risk of falls and temporary motor impairments. Additionally, antidepressants, particularly tricyclic ones, may cause intensified side effects such as dizziness and heart palpitations [19].
Thorough Medical Assessment by Experienced Cannabis Physicians Is Essential
To prevent unwanted interactions, it is crucial to align cannabis therapy—since its effects vary depending on the preparation and method of administration—with the patient’s medical history and current medications. However, such an adjustment requires a thorough medical evaluation. This is why the expertise of physicians with specialized knowledge of the applications, benefits, and limitations of medical cannabis is necessary to ensure that patients receive a safe and personalized treatment.
The doctors at Nowomed specialize in the therapeutic use of cannabis. Their expertise allows them to provide professional support for cannabis therapy, prevent side effects, and tailor treatment—including strain selection and dosage—to the individual needs of patients.
To get in touch with the Nowomed doctors, you can register for free and fill out an anamnesis form. Afterward, you have the option to book an initial consultation to determine your eligibility for cannabis therapy.
Possible Cost Coverage by Health Insurance
In Australia, access to medical cannabis is regulated under the Special Access Scheme (SAS) and the Authorised Prescriber (AP) Scheme. In most cases, medical cannabis is not subsidised under the Pharmaceutical Benefits Scheme (PBS), meaning patients typically need to cover the costs themselves. However, some private health insurers may offer partial reimbursement for medical cannabis prescriptions, depending on the policy.
If medical cannabis is prescribed, it is usually done through a private prescription, requiring patients to pay out-of-pocket. Since this can be a financial burden, individuals should check with their private health insurance provider or explore potential clinical trials or compassionate access programs that may assist with costs.
Summary
Which Medications Are Incompatible with Cannabis?
Medical cannabis offers many therapeutic possibilities, but it requires careful consideration of potential contraindications and interactions. Certain patient groups face a higher risk of adverse effects, making particular caution necessary for individuals with severe mental illness, pregnant and breastfeeding women, and patients with a history of substance use disorders. Therefore, an individual medical assessment is essential to minimize risks.
Consultation with experienced physicians specializing in cannabis therapy ensures a personalized treatment plan, as this is the only way to avoid contraindications and prevent unexpected interactions. Conversely, incorrect or inadequate use may lead to undesirable side effects.
Applying for Cannabis Therapy
If you would like to find out whether you are eligible for cannabis therapy, you can register for free with nowomed. However, before treatment can begin, patients must complete a medical history form to allow physicians to make an informed assessment. Once completed, you can schedule an initial consultation with our doctors.
Since comprehensive medical advice is crucial, this consultation will provide you with detailed information about your suitability for cannabis treatment, an explanation of the therapy process, and the opportunity to ask any questions. If deemed eligible, you will receive an initial prescription, allowing you to purchase the appropriate cannabis preparation from a pharmacy.
FAQs
Who Should Not Use Medical Cannabis?
Individuals with severe mental illnesses, heart conditions, or a history of substance use disorders are generally not suitable for medical cannabis treatment, as the potential risks may outweigh the therapeutic benefits. Additionally, pregnant and breastfeeding women should avoid using medical cannabis to prevent potential health risks for the child.
Does Medical Cannabis Interact with Other Medications?
Cannabis has several interactions with other medications because it affects certain enzymes responsible for drug metabolism. These interactions should be carefully evaluated before therapeutic use to avoid unwanted side effects. The primary medications of concern include anticoagulants such as warfarin, antidepressants, and sedatives.
Is Medical Cannabis Legal in Australia?
Yes, medical cannabis is legal in Australia, but it is a regulated prescription medication. Patients can access it only through approval pathways such as the Special Access Scheme (SAS) or the Authorised Prescriber (AP) Scheme. Prescriptions must be issued by registered medical practitioners, and not all doctors are authorised to prescribe it. Dentists and veterinarians cannot prescribe medical cannabis for human patients.
What Are the Requirements for Accessing Medical Cannabis in Australia?
To obtain medical cannabis from a pharmacy in Australia, patients must have a valid prescription from an approved prescriber. The prescribing doctor must apply for Therapeutic Goods Administration (TGA) approval under the SAS or AP Scheme before issuing the prescription.
Medical cannabis may be prescribed for various conditions, including chronic pain, migraines, anxiety disorders, sleep disorders, nausea, and loss of appetite. There is no single qualifying condition for treatment, as prescriptions are based on individual patient needs. However, doctors must determine that medical cannabis is clinically appropriate and that conventional treatments have been ineffective or unsuitable before approving its use. [22]
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