Does cannabis interact with antidepressants or lithium?
Cannabis and antidepressants
Cannabis or marijuana can interact with tricyclic antidepressants (TCAs), such as amitriptyline, imipramine and dothiepin.
Both cannabis and TCAs can cause an abnormally fast heartbeat (tachycardia) and high blood pressure (hypertension). There’s also a risk of other side effects, such as confusion, restlessness, mood swings and hallucinations.
There’s a risk that using cannabis while you’re on any of these medicines could lead to problems such as tachycardia, even if you don’t already have a heart condition.
Little research has been done into the interaction of cannabis with other types of antidepressants, such as SSRIs.
Cannabis and lithium
Lithium is used to treat bipolar disorder, a condition where people can switch between depression and extreme excitement and agitation (mania).
There’s little evidence to suggest that people who use cannabis should normally not take lithium, but this hasn’t been properly researched.
Side effects of cannabis
It’s not clear how often cannabis itself can cause anxiety or depression, but research suggests this can happen.
It’s therefore recommended that if you’re anxious or depressed and you use cannabis regularly, you should try giving up and see if that helps.
Tachycardia, dizziness, anxiety, drowsiness, nausea and vomiting, difficulty sleeping and confusion are all possible side effects of cannabis.
These side effects can also be caused by certain antidepressants, so using cannabis at the same time can make them worse.
If you have any concerns about the medicines you’re taking, talk to your GP or pharmacist.
You can also phone NHS 111 or Talk to Frank, a friendly confidential drugs helpline, on 0300 123 6600.
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Page last reviewed: 27 March 2018
Next review due: 27 March 2021
Cannabis or marijuana is usually smoked and typically mixed with tobacco. It can interact with certain types of antidepressants, such as tricyclic antidepressants (TCAs), which share similar side effects.
How Cannabis Interacts With Antidepressants
Cannabis and antidepressants both work to boost happy brain chemicals, and even give rise to the creation of new brain cells. However, using the two together can result in potentially dangerous interactions. Some antidepressants don’t mix with cannabis, whereas others are much more compatible. Find out about these interactions in detail below.
The relationship between cannabis, mental health, and antidepressants.
Cannabis and mental health share a controversial—and at times paradoxical—relationship. Some cannabis smokers use the herb to elevate their spirits and boost their mood, and some even need the plant to help them get out of bed in the morning. In others, cannabis can invoke feelings of paranoia and other mood disturbances.
There are conflicting views in healthcare when it comes to cannabis and depression. Some practitioners hold the belief that cannabis may help to take the edge off some symptoms, whereas others believe excess cannabis use leads to symptoms of depression and interacts dangerously with conventional medication for the condition.
Continue reading to explore the relationship between cannabis, depression, and antidepressant medication.
Cannabis and Mental Health: A Complicated Relationship
Cannabis affects different people in different ways, especially when it comes to mental health. Most people familiar with the effects of the herb will vouch that it does a reliable job of improving mood. A few tokes on a joint can boost dopamine levels, reduce feelings of nervousness, and soothe the body.
These outcomes help many people across the world deal with certain mental health conditions. However, research also associates cannabis with adverse mental health outcomes. Although no research draws a direct link between consuming cannabis and depression, surveys report a high incidence of depression in heavy cannabis smokers  compared to non-smokers.
Cannabis may also trigger underlying health mental conditions in some individuals. The psychotropic effects of the herb can stoke symptoms of schizophrenia and psychosis—serious mental health disorders—in those predisposed to the conditions.
The cannabinoid THC produces the psychotropic effects of cannabis; however, over 100 cannabinoids exist in the plant, and most are non-psychotropic. In fact, molecules such as CBD can help to inhibit some of the effects of THC, and show potential in the field of mental health  .
Cannabis and Antidepressants
Staggeringly, over 260 million people  across the world suffer from depression, and millions take antidepressant medication  to manage their symptoms. However, people with depression are more likely to smoke cannabis. Both weed and antidepressants create profound short and long-term changes in the brain, and frequently interact with each other. Before we delve into the safety issues of this combination, let’s explore the unique effects of each drug.
How Does Cannabis Affect the Body?
Cannabis interacts with several major physiological systems. As their names suggest, cannabinoids primarily target the endocannabinoid system (ECS). The ECS plays a fundamental role by regulating many other systems and helping the body maintain biological equilibrium, aka homeostasis.
The ECS features three main components: receptors, signalling molecules (endocannabinoids), and enzymes that create and break down these molecules. Interestingly, cannabinoids such as THC share a similar molecular structure with endocannabinoids, allowing them to bind to the same receptors.
After taking a hit from a joint or bong, THC diffuses through the alveoli in the lungs, enters the bloodstream, and passes into the brain. Here, the molecule binds to CB1 receptors of the endocannabinoid system, where it gives rise to its psychotropic effects—a high.
This binding also boosts dopamine levels and neuronal activity in the brain. Dopamine plays a role in the brain’s reward system and makes us feel pleasure after consuming a certain substance or acting in a certain way.
This surge in feel-good neurotransmitters might help some users feel relief from their depression symptoms, at least for a while. However, with long-term use, THC begins to blunt the dopamine system  and may even block the dopamine response to other stimuli that usually release the chemical.
The neurogenesis hypothesis suggests that depression may arise from an alteration in the creation of new neurons in the brain  . The rate of neurogenesis may underpin a healthy and happy brain. Negative events, such as stressful or traumatic experiences, may alter this rate, leading to depression. Evidence suggests that the endocannabinoid system helps to regulate neurogenesis, and cannabinoids such as THC and CBD may help drive this process  in the brain.
CBD also interacts with numerous bodily systems, including serotonin pathways. As a key regulator of mood and feelings of well-being, serotonin plays an important part in how we feel. The ability of CBD to interface with this system means the cannabinoid may help to take the edge off feelings of nervousness and agitation  .
How Do Antidepressants Affect the Body?
Antidepressants ultimately aim to improve the symptoms of depression by altering brain chemistry. Although depression has no single cause, a shift in neurochemistry following addiction, emotional life events, or genetic factors may lead to feelings of hopelessness, low mood, and low self-esteem.
Antidepressant medication helps to regulate neurological activity by interacting with systems in the brain that govern mood. Some of these chemicals seek to increase and prolong the presence of brain chemicals, such as serotonin, in the synaptic space. Research also suggests that antidepressants might improve depression symptoms by improving neurogenesis rates within the depressed brain, similar to cannabis.
Interestingly, antidepressants appear to recruit the endocannabinoid system  , and prolonged use may be involved in long-lasting neuroplastic changes in the brain.
Cannabis’ Interaction With Antidepressants
Because both cannabis and antidepressants may provide symptomatic relief, some users might think taking the two together will provide even better results. However, taking cannabis alongside conventional medication can produce dangerous side effects when done incorrectly. Check out the list below to find out which antidepressants interact with cannabis.
Types of Antidepressants
The following drugs may fall into the same “antidepressant” category, but they work in a variety of ways. Varying mechanisms of action mean different drugs interact with cannabis in more or less dangerous ways. Take a dive into the most common antidepressants below and find out if they are safe to take alongside the herb.
Tricyclics are among the oldest antidepressants developed. Due to their early occurrence, they generally produce more side effects than newer medications. Known by the brand names Tofranil and Surmontil, tricyclics work by changing brain chemistry. These molecules block the reuptake of the neurotransmitters norepinephrine and serotonin, ultimately boosting their levels in the brain.
Potential Side Effects
Common side effects of tricyclics include drowsiness, constipation, blurred vision, and a drop in blood pressure. Unfortunately, these medications have a high likelihood of negatively interacting with cannabis. Possible side effects of combining the two include potentially life-threatening increased heart rate (tachycardia).
Selective Serotonin Reuptake Inhibitors (SSRIs)
Selective serotonin reuptake inhibitors include branded drugs such as Prozac. These drugs interact with serotonin receptors in the brain, latching onto these sites in the synapses of neurons and preventing cells from reabsorbing serotonin. High levels of serotonin remain in the synaptic space, where it exerts mood-enhancing effects.
Potential Side Effects
Taken alone, SSRIs can produce side effects such as anxiety, shaking, weight loss, and dizziness. These drugs also pose a low–moderate risk of negatively interacting with cannabis.
Monoamine Oxidase Inhibitors (MAOIs)
Monoamine oxidase inhibitors work by prolonging the presence of neurotransmitters in the brain. Dopamine, serotonin, and norepinephrine all fall into the monoamine chemical class. The enzyme monoamine oxidase metabolises and breaks down these molecules. By inhibiting the action of these enzymes, MAOIs lead to enhanced levels of monoamines in the synapses.
Potential Side Effects
MAOIs negatively interact with a long list of foods, including soy, salami, sauerkraut, cheese, and nuts. Common side effects of the medication include fatigue, muscle aches, insomnia, and reduced libido. MAOIs can interact dangerously with cannabis, and the combination should be avoided.
Newer Antidepressants (SNRIs)
Serotonin and norepinephrine reuptake inhibitors (SNRIs) are used to treat symptoms of depression, such as irritability and sadness. Doctors also prescribe these drugs, under the brand names Fetzima and Cymbalta, to treat anxiety disorders and nerve pain. SNRIs work by blocking the reuptake of both serotonin and norepinephrine.
Potential Side Effects
Frequent side effects of SNRIs include dry mouth and excessive sweating. SNRIs are relatively safe for most people, and they pose a low–moderate risk of negatively interacting with cannabis.
Risk Factors of Combining Cannabis With Antidepressants
Combining cannabis with antidepressants poses several risks. The herb produces the most dangerous outcomes when combined with tricyclics and MAOIs. However, it may be safe to smoke while taking newer medications such as SSRIs.
You should always consult your physician before combining cannabis with any antidepressant to ensure you’re making a safe decision that won’t put your life in danger. Depending on your personal and family history, among other factors, your risk of having an adverse reaction could be more or less likely.
Does Cannabis Interact With Other Mental Health Medication?
Cannabis may also interact with the common anti-anxiety drug class benzodiazepines (e.g. Xanax). Although no research documents any interaction between the two substances, both work as central nervous system depressants. Moreover, both substances may help to ease feelings of nervousness when taken in low doses, while high doses may give rise to paranoia and rapid heart rate.
Mixing Xanax and cannabis may result in side effects such as dizziness, drowsiness, trouble concentrating, slurred speech, and confusion. Cannabis can also interact with other mental health medication, including sedatives such as Ambien.
What About CBD and Antidepressants
CBD poses a relatively high risk of interacting with antidepressants. Although the cannabinoid doesn’t produce psychotropic effects, it does cause shifts in brain chemistry and liver metabolism. CBD can slow down how fast the liver processes antidepressants, causing elevated levels to circulate around the body. Discuss CBD with your doctor before combining it with antidepressants to make sure you do so safely.
Can You Mix Cannabis and Antidepressants?
Yes and no. Some antidepressants cause dangerous interactions with cannabis; others are relatively safe to take at the same time. Ultimately, you should consult a healthcare professional if you wish to use cannabis and antidepressants together. The combination may provide enhanced results, but you need to ensure you’re being as safe and responsible as possible.
Both cannabis and antidepressants are used by people with depression. However, taking them at the same time requires careful consideration. Find out more.