Medical cannabis: effects, uses, forms and risks

There are very conflicting views circulating about cannabis as a medicine: some see it as a remedy that helps with almost everything, whilst others view it as recreational use with a medical label. Here you can find out what medical cannabis actually is, how it works, where it is used medically and what risks are associated with it.

Key points at a glance

• Medical cannabis refers to cannabis-based medicines prescribed by a doctor and dispensed through pharmacies. The Medical Cannabis Act has been in force since 1 April 2024. This framework is clearly distinct from private consumption.
• The two main active ingredients are THC and CBD. THC has a psychoactive effect, whilst CBD does not, and both interact differently with the body’s endocannabinoid system.
• There is no single ‘effect of cannabis’. The quality of the available data depends on the clinical presentation, the active ingredient and the form of administration.
• According to the prescribing information for authorised cannabis-based medicines, tiredness and dizziness are among the very common side effects. Whether treatment is an option at all can only be determined following a medical examination.

What distinguishes medical cannabis from recreational use

The difference lies not in the plant itself, but in the context surrounding it. Medical cannabis products are manufactured to pharmaceutical standards, their active ingredient content is defined and documented, and they are prescribed for a specific set of symptoms.

There have also been some legal changes. Since 1 April 2024, medical cannabis is no longer covered by the Narcotics Act, but is regulated by the Medical Cannabis Act. Since then, it has been prescribed on a standard prescription, usually an e-prescription, and no longer on a narcotics prescription. The synthetic active ingredient nabilone is an exception. The blanket statement ‘cannabis is a narcotic’ is therefore no longer accurate.

The fact that personal consumption is permitted under certain conditions does not, however, mean that cannabis therapy is a matter of personal judgement: it requires a diagnosis, a risk-benefit assessment and medical supervision.

How THC and CBD work and what forms they come in

The body has its own regulatory system that plays a role in pain processing, appetite, sleep, mood and muscle tension. This endocannabinoid system responds to the body’s own neurotransmitters, and cannabinoids from the plant bind to the same receptors. THC has a stronger effect on receptors in the nervous system and is responsible for the intoxicating effect. CBD has a significantly weaker effect on the same receptors, does not cause intoxication and is being investigated, amongst other things, for its potential anti-inflammatory and antispasmodic properties.

In practice, you will encounter three groups: dried flowers for inhalation via a vapouriser, standardised extracts in the form of oils or solutions, and authorised proprietary medicinal products that have undergone the standard authorisation procedure. The active ingredient dronabinol, i.e. isolated THC, is predominantly produced in Germany as a compounded preparation in pharmacies and is not a ready-to-use medicinal product. The groups differ in terms of how precisely the active ingredient content is defined and how the effects unfold. Inhaled preparations tend to take effect more quickly and last for a shorter time, whilst those taken orally take longer to take effect and last for a longer time. There are no universally applicable figures on this, as both depend on the preparation, the method of administration and the individual.

Conditions for which medical cannabis is used

It is not possible to draw up a reliable list of conditions for which cannabis is a proven remedy. It makes more sense to ask how robust the evidence is for a particular set of symptoms and a specific product.

Its use has been most thoroughly investigated where authorised ready-to-use medicinal products exist: for spasticity associated with multiple sclerosis, and for nausea and vomiting associated with chemotherapy. In the case of chronic pain – by far the most common reason for prescribing – the effects measured in controlled trials are, on average, small. In the accompanying survey by the Federal Institute for Drugs and Medical Devices, more than three-quarters of treatments were for chronic pain; this does not prove efficacy. There is currently no specialist guideline specifically on cannabis therapy.

Recent controlled studies have investigated very specific issues, such as a full-spectrum extract for chronic lower back pain or a vaporised preparation for acute migraine. This is the crucial point: a positive result applies, first and foremost, to the specific preparation and patient group under investigation, not to every cannabis strain, every oil or every other condition.

What side effects and risks are known

Cannabis-based medicines are not harmless natural products. Dizziness and tiredness are listed as ‘very common’ in the prescribing information for an authorised cannabis-based medicine, meaning they occur in more than one in ten people receiving treatment. Other common side effects include drowsiness, dry mouth, difficulties with concentration and memory, balance problems, gastrointestinal complaints, and changes in heart rate and blood pressure. Preparations containing THC may also cause restlessness, anxiety or a depressed mood.

Particular caution is required in cases of pre-existing mental health conditions. Known or suspected schizophrenia or any other psychotic disorder, including a family history of such conditions, is an explicit contraindication for a licensed cannabis-based medicinal product. Cardiovascular diseases, pregnancy and breastfeeding, as well as age, must also be taken into account. Interactions are also relevant, for example with sedative medicines and with active substances that are metabolised via the same pathways in the liver. A complete list of all medicines and dietary supplements should therefore be discussed during the consultation with the doctor.

One aspect that is often underestimated in everyday life concerns fitness to drive. Since August 2024, a statutory THC limit of 3.5 nanograms per millilitre of blood serum has applied to road traffic. Anyone taking a medicine prescribed by a doctor for a specific medical condition in accordance with the instructions is exempt from this administrative offence; separate, stricter rules apply to new drivers and those under the age of 21. This exemption is not a carte blanche: anyone who is actually unfit to drive is liable to prosecution, regardless of whether they have a prescription, and fitness to drive is assessed on a case-by-case basis. Reaction times may be impaired, particularly at the start of a course of treatment, and this is a matter that must be explicitly addressed by the treating practitioner.

Finally, habituation and dependence are possible. According to the prescribing information, the risk is considered low for an authorised finished medicinal product, but is assessed as higher for preparations with a high THC content. This is another reason why follow-up checks are part of the process.

How decisions are made regarding cannabis-based therapy and how it is monitored

The process begins not with a prescription, but with an assessment: medical history, current symptoms, previous treatment attempts and any potential contraindications. This determines whether a cannabis-based medicine might be medically appropriate and which dosage form is best suited to the patient’s situation.

A specific diagnosis does not automatically lead to a prescription, nor is the prescription the end of the process: efficacy, tolerability and treatment goals are monitored throughout the course of treatment, and treatment may be adjusted or discontinued if it proves ineffective.

The issue of costs is a separate matter. Whether a medicine may be prescribed and whether statutory health insurance covers it are two different matters. Since 30 July 2026, dried flowers have no longer been eligible for prescription at the expense of statutory health insurance. Since then, entitlement has covered extracts of standardised quality, as well as dronabinol and nabilone, subject to a six-month trial of treatment with an authorised finished medicinal product.

The best way to find out whether cannabis therapy is even an option in your situation is to consult a practice with experience in cannabinoid therapy. Find doctors with experience in medical cannabis therapy

Frequently Asked Questions

Is CBD from the chemist’s the same as medical cannabis?

No. Over-the-counter CBD products are not prescription medicines and are subject to different requirements regarding composition and quality testing. If you use such products, this should still be discussed with your doctor.

Is medical cannabis addictive?

Dependence is possible, particularly with preparations containing THC. The level of risk depends on the active ingredient, the duration of use and risk factors. Tolerance may also develop. Both are monitored as part of supervised treatment.

Can any doctor prescribe medical cannabis?

In principle, yes. The Medical Cannabis Act does not stipulate that prescriptions must be issued by a specialist, but excludes dentists and veterinary surgeons from the authority to prescribe. For a prescription to be covered by health insurance, prior authorisation is usually also required; however, certain specialist, sub-specialist and additional qualifications have been exempt from this requirement since October 2024.

Classification

Medical cannabis is neither a miracle cure nor a fringe phenomenon, but a treatment option whose benefits can only be assessed over time. Because pre-existing conditions, previous treatments and other medicines significantly influence the assessment, the process requires an individual medical evaluation. View cannabis doctors in your area