8 Side Effects of Cannabis (Weed) You Should Be Aware of

Laws and public opinions are changing around cannabis, also known as weed or marijuana. As access to cannabis increases, more people are interested in using it for various health conditions or as an alternative to alcohol or other drugs.

Although it’s true that cannabis may be a safer alternative to some other substances, it still has a number of side effects to be aware of. Some are short-term side effects that go away when cannabis wears off. But others are more serious, long-term side effects that could impact your health.

Cannabis side effects at a glance

Below is a list of possible cannabis side effects. Most weed-related side effects are associated with tetrahydrocannabinol (THC). But a few are more likely with cannabidiol (CBD). 

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Must be 21 years or older to purchase. Cannabis is not recommended for women who are pregnant or nursing or those who are suffering from bipolar disorder or schizophrenia. Cannabis use may increase risk of falls. Always consult with your doctor before beginning any new medical treatment.

Keep in mind, this isn’t a comprehensive list. There are many different types and strengths of cannabis, and everyone responds to cannabis differently. So, you may experience side effects that aren’t listed here. And some side effects are more likely if you consume cannabis along with other medications or substances. It’s best to discuss any concerns about the side effects of cannabis with your healthcare provider.

Short-term side effects:

• Feeling “high” or “stoned”

• Dizziness

• Drowsiness

• Red eyes

• Dry mouth

• Increased appetite

• Fast heart rate

• Diarrhea (with CBD use)

• Short-term memory issues

• Anxiety

• Paranoia

• Losing track of time

• Feeling sad or depressed

• Trouble thinking clearly

• Trouble with coordination

• Orthostatic hypotension (low blood pressure after standing up)

• Psychosis, including hallucinations or delusions

Long-term side effects:

• Cannabis use disorder

• Lung problems (due to smoking or vaping cannabis)

• Increased risk of heart disease, heart attack, and stroke

• Depression

• Cannabis hyperemesis syndrome

• Withdrawal symptoms (trouble sleeping, irritability, headache)

• Mood disorders

• Impaired brain development (with chronic use prior to age 25)

• Liver problems (CBD)

• Increased risk of severe mental illness, including schizophrenia

Let’s take a closer look at eight cannabis side effects in greater detail.

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1. Feeling high

The “stoned” or “high” feeling that can happen when you consume cannabis may be a desired effect for some people. But for others, such as those using cannabis for medical reasons, it may be an unwanted side effect. And it can be unpleasant for anyone if this side effect is more intense than expected.

The best way to avoid this side effect is to choose cannabis products that are low in THC. It’s also best to start with a small amount of cannabis and wait for it to kick in before consuming more. This gives you more control over how it affects you. Use extra caution with cannabis edibles, as it can take longer than expected to feel their effects.

If you find yourself feeling too high after consuming cannabis, try to stay calm. You may feel anxious or uncomfortable, but serious complications from consuming too much cannabis are rare. Find a distraction, such as listening to music or taking a walk if you feel you can do so safely. The intensity should lessen after an hour or so.

2. Fast heart rate

Cannabis can make your heart beat faster, especially if it’s high in THC. In most cases, this isn’t a serious issue, and your heartbeat will return to normal after a short time. But consuming cannabis frequently could raise your risk of a heart attack or stroke. And the risk is greater if you have a heart condition such as high blood pressure or an irregular heartbeat.

If you have a heart condition, it’s best to speak with your healthcare provider before consuming cannabis that contains THC. If at any point after consuming cannabis you have chest pain or trouble breathing, seek medical care right away. 

3. Increased appetite

Another common THC side effect is an increased appetite, often referred to as “the munchies.” THC can make you feel hungry, even if you’ve recently eaten. It also enhances your desire for sweet and fatty foods. This can be a helpful side effect if you’re having trouble with nausea or don’t have an appetite. But for others, it may be bothersome or lead to unhealthy food choices.

Lowering your THC dosage or choosing cannabis products with less THC can help prevent this side effect. It may also be helpful to keep healthy snacks at hand, such as nuts, hummus, and fresh fruit.

Good to know: Even though cannabis can increase your appetite, there’s some evidence that those who consume cannabis actually weigh less on average than those who don’t. It’s not clear why this is the case, but it may help ease your mind if you’re concerned about weight gain from the munchies.

4. Cannabis hyperemesis syndrome

Cannabis is known for its anti-nausea effects. But it can also cause repeated cycles of vomiting for some people, known as cannabis hyperemesis syndrome (CHS). CHS happens most often after large doses of THC or consuming large amounts of cannabis over a long period of time.

If you experience severe or non-stop vomiting after consuming cannabis, you may be experiencing CHS. Taking a hot shower or applying a layer of capsaicin cream to your stomach may help. But if you’re unable to stop vomiting on your own, it’s best to seek medical care. CHS can lead to dehydration, which can be dangerous if not treated properly.

Consuming lower amounts of THC and taking frequent breaks from using cannabis may help lower your risk of CHS, but there’s not a guaranteed way to prevent it. Some people may be more likely to develop CHS based on inherited traits, but more research is needed to know for sure. Once you’ve developed CHS, the only way to avoid it is to stop consuming cannabis.

5. Withdrawal symptoms

If you consume cannabis often, you may experience withdrawal symptoms if you stop consuming it abruptly. Normally, these symptoms peak in the first week after you stop using cannabis, but they can last for 2 weeks or longer for some people. The good news is that unlike other substances, cannabis withdrawal isn’t likely to be dangerous or harmful to your health.

Common cannabis withdrawal symptoms include:

• Irritability

• Anxiety

• Sleeping problems

• Loss of appetite

• Depressed mood

Most people can manage these side effects on their own and return to feeling normal quickly. But if they aren’t improving, or you have more serious symptoms such as stomach pain, sweating, or shakiness, talk to your healthcare provider. They can help manage your symptoms safely.

6. Cannabis use disorder

Cannabis is a controlled substance, which means it carries a risk of dependence and misuse. It’s estimated that about 9% of people who consume cannabis may develop cannabis use disorder. Cannabis use disorder is defined as having two or more of the following:

• Consuming cannabis in larger amounts or more often than intended

• Being unable to control cannabis use 

• Spending a lot of time getting, using, or recovering from cannabis

• Experiencing strong cravings to consume cannabis

• Having problems at home, school, or work caused by consuming cannabis

• Continuing to consume cannabis, even when it is causing legal, mental, or physical problems

• Needing to use more cannabis or a stronger type to get the same effect

• Consuming cannabis to avoid withdrawal symptoms

The risk for cannabis use disorder goes up if you have a history of substance misuse or consume cannabis before the age of 18. Genetics and other social or health issues can also make it more likely. If you’re concerned about cannabis use disorder, speak to a loved one or a healthcare professional. They can help you find the support and treatment you need.

7. Increased risk of heart problems

The regular consumption of cannabis is associated with an increased risk of heart disease, heart attack, and stroke. A 2024 study of over 400,000 people showed that cannabis use is associated with heart problems. And the more often it’s consumed, the greater your risk.

If you have a history of heart problems, talk to a healthcare professional before consuming cannabis for any reason. And it’s best to keep your cannabis consumption to a minimum to limit this risk, unless instructed otherwise by a medical professional. 

8. Mental health issues

Several studies have shown an association between consuming cannabis and an increased risk for certain mental health issues, such as schizophrenia. But it’s not clear if cannabis actually causes schizophrenia, or if people living with schizophrenia are simply more likely to self-medicate with cannabis.

Regular cannabis use is also associated with an increased risk of depression, anxiety, and suicidal thoughts in some people. Again, there’s not clear evidence that cannabis actually causes these problems, but it’s still good to be aware of the possibility. 

If you have a history of mental health problems, cannabis may worsen your symptoms. So, it may not be a good choice for you. Talk to your healthcare provider first to see if cannabis may be a safe option for you. If at any point you or a loved one notice a concerning change in your behavior during or after consuming cannabis, seek medical care.

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Written by:

Stacia Woodcock, PharmD

Stacia Woodcock, PharmD, is a pharmacy editor for GoodRx. She earned her Doctor of Pharmacy degree from the University of Kentucky and is licensed in New York and Massachusetts.

Edited by:

Sophie Vergnaud, MD

Sophie Vergnaud, MD, is the Senior Medical Director for GoodRx Health. An experienced and dedicated pulmonologist and hospitalist, she spent a decade practicing and teaching clinical medicine at academic hospitals throughout London before transitioning to a career in health education and health technology.

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