A drug interaction is a drug situation in which the activity of a drug is affected by another substance (usually another drug) when both are administered together. Due to its broad range of effects, Cannabis can cause a variety of interaction effects with many over-the-counter and prescription medications, as well as most recreational drugs. This pamphlet contains a series of generalized guidelines intended toinform about possible side effects that can occur with the various major classes of drugs.
Under no circumstances should any person augment or substitute any prescribed medication with another registered drug or other (alternative, complementary or herbal) treatment without first consulting with a healthcare professional. This pamphlet is intended solely as an introduction to the most common drug interactions and is by no means an exhaustive exploration of the possible dangers inherent in modifying an ongoing pharmaceutical regimen.
Antiepileptic drugs (also known as antispasmodics or anticonvulsants) are a diverse group of pharmaceuticals used in the treatment of epileptic seizures. They are also increasingly being used in the treatment of bipolar disorder, since many seem to act as mood stabilizers, and for treatment of neuropathic pain.
Antiepileptic medications share memory loss related side effects with cannabis. Both in conjunction may increase the severity of these effects, increasing the likelihood of forgetting a timed dose of medication and therefore leading to the possibility of an increased number of seizures occurring.
Unfortunately, little is known about the interactions between many of these medications and cannabis. If the choice is made to introduce cannabis into a pre-existing regimen of antiepileptic drugs (especially combinations of such), great care should be taken to ensure a safe environment in the case of seizure and to make careful note of any changes in the frequency or severity of any seizures experienced.
Antipsychotics are a diverse class of psychiatric medications primarily used to manage psychosis, particularly in schizophrenia and bipolar disorder, and are increasingly being used in the management of non-psychotic disorders.
Relevant data in regards to interactions between these medications and cannabis is lacking. Recent evidence suggests that antipsychotic treatment may have effects within the endocannabinoid system (the same system on which cannabis exerts an effect). However the clinical relevance of this is unclear.
While many individuals who suffer from schizophrenia self-medicate with cannabis, the majority of clinical data indicates an increase in the positive symptoms associated with schizophrenia (including delusions, hallucinations and disordered thoughts) in association with cannabis use. For patients with established schizophrenia, cannabis use is clinically associated with increased risk of relapse, and poorer adherence to the antipsychotic treatment.