What happens if I consume too much CBD? Understanding safety and side effects

October 12, 2025 •

6 min read

According to a 2011 review published in Current Drug Safety, a toxic dose of CBD was estimated at around 20,000 mg in a single sitting, an amount far exceeding what an average person would typically consume. While a fatal overdose of pure CBD is highly unlikely, consuming too much CBD can lead to some unpleasant, though usually temporary, side effects. This article explores what happens if I consume too much CBD and how to avoid adverse reactions by understanding proper dosages and potential risks.

Quick Summary

Taking excessive amounts of CBD may cause mild, temporary side effects like drowsiness, dry mouth, diarrhea, and appetite changes. A lethal overdose of pure CBD is not a concern, but high doses could interact with other medications and affect liver enzymes. Proper dosing and product quality are crucial to minimize risks.

Key Points

Lethal Overdose is Unlikely: A fatal overdose from pure CBD is highly improbable, as it does not affect critical brain functions like breathing.
Excessive Doses Cause Mild Side Effects: Taking too much CBD can lead to temporary discomforts like drowsiness, dry mouth, diarrhea, and changes in appetite.
High Doses Can Affect the Liver: Extremely high, long-term CBD use can cause elevated liver enzymes, particularly when combined with certain medications.
Drug Interactions Are a Risk: CBD inhibits the CYP450 enzyme system in the liver, which can dangerously alter the concentration of other medications in your system.
Proper Dosing is Key to Safety: To prevent adverse effects, start with a low dose and increase gradually while monitoring your body's response.
Quality Matters: Due to lack of regulation, buying CBD from a reputable, third-party lab-tested source is crucial to avoid contaminants like THC or heavy metals.
What to Do if You Take Too Much: If you experience adverse effects, stay calm, hydrate, and eat a light snack. The effects are temporary.
When to Seek Medical Help: Consult a doctor if you experience severe or persistent symptoms, especially if you take other medications or have underlying health conditions.

Can you overdose on CBD? What research and experts say

While the idea of a fatal overdose is a serious concern with many substances, a lethal overdose of pure CBD is highly unlikely. Unlike THC, which binds to brain receptors that can cause a high, CBD does not affect the brainstem areas that control breathing, making it very safe in this regard. However, the term "overdose" can also refer to taking more of a substance than intended, leading to adverse effects, and this is possible with CBD. Consuming extremely high doses, such as the estimated 20,000 mg needed for toxic effects in some studies, would be extremely difficult to do unintentionally. For the average user, the primary risk of taking too much CBD is experiencing unpleasant, non-life-threatening side effects.

Common side effects of excessive CBD consumption

Even in non-toxic but large quantities, CBD can cause some uncomfortable side effects. These effects are typically temporary and resolve as the body processes the excess compound.

Drowsiness and Fatigue: As CBD has calming properties, a high dose can lead to significant drowsiness and lethargy. For some, this may be a desired effect, but for others, it can interfere with daily activities.
Gastrointestinal Issues: Many users report stomach discomfort, including nausea, vomiting, and diarrhea. This can be due to the CBD itself or the carrier oil (like MCT oil) used in the product.
Dry Mouth: Often called "cottonmouth," this is a common side effect of cannabinoids, as they can inhibit saliva production. Drinking plenty of water can help mitigate this symptom.
Changes in Appetite: Some individuals experience a reduced appetite, while others notice an increase. This effect varies from person to person.
Dizziness or Lightheadedness: High doses of CBD can cause a temporary drop in blood pressure, leading to feelings of dizziness. This is particularly relevant for those with already low or normal blood pressure.

More serious concerns with high-dose CBD

While mild side effects are the most common issue, there are more serious considerations to be aware of, especially with high doses or long-term use.

Liver Enzyme Abnormalities: High doses of CBD have been associated with abnormalities in liver-related blood tests. The FDA, during its review of the prescription drug Epidiolex, identified potential for liver injury, especially when taken with other liver-affecting medications. Regular users of high doses should have their liver enzymes monitored by a healthcare provider.
Drug Interactions: CBD inhibits the cytochrome P450 (CYP450) enzyme system, which is responsible for metabolizing many drugs. This can affect the levels of other medications in the bloodstream, either increasing their concentration to potentially toxic levels or decreasing their effectiveness. It is crucial to consult a doctor before combining CBD with other medications, particularly blood thinners, certain antidepressants, and anti-epileptic drugs.
Contaminants in Unregulated Products: The unregulated nature of the CBD market is a significant safety concern. Products may be mislabeled regarding CBD content or, worse, contain harmful contaminants like pesticides, heavy metals, or undisclosed THC. Always choose products from reputable manufacturers that provide third-party lab testing results.

Factors influencing your reaction to too much CBD

Several individual factors can influence how your body reacts to a high dose of CBD:

Body Weight and Metabolism: A person's weight and metabolic rate will affect how quickly they process CBD. Heavier individuals may require more to feel effects, while those with slower metabolism may feel stronger effects from a smaller dose.
Tolerance: Regular CBD users may develop a tolerance over time, requiring a higher dose to achieve the same effect. New users, however, may find even a moderate dose to be "too much" for their system initially.
Product Type and Concentration: The method of consumption (e.g., oil, edibles, vapes) and the product's concentration will affect the speed and intensity of the effects. For instance, edibles take longer to kick in and can have more prolonged effects.
Other Medications or Supplements: As mentioned, interactions with other substances can significantly alter how CBD affects you.

How to avoid taking too much CBD

Preventing the negative side effects of excessive CBD is straightforward with a cautious approach. The key is to find your personal "therapeutic zone"—the dosage that provides benefits without adverse effects.

Start Low and Go Slow: This is the golden rule for all CBD use. Begin with a minimal dose (e.g., 5–10 mg) and gradually increase it over several days, monitoring how you feel.
Read the Label: Pay close attention to the product's packaging. It should clearly state the total milligrams of CBD and the amount per serving (e.g., mg per drop or per gummy).
Keep a Journal: A journal can be a valuable tool for tracking your dosage, timing, and the effects you experience. This can help you identify your ideal amount more accurately.
Buy Quality Products: Stick with reputable brands that provide a Certificate of Analysis (COA) from a third-party lab. This confirms the product's potency and verifies it is free from contaminants.

Side effects of too much CBD vs. standard dosage

To better understand the difference, consider the effects of a standard, recommended dose versus an excessive one.


Feature	Standard Dosage (e.g., 20-100 mg/day)	High/Excessive Dosage (e.g., 1,500+ mg/day)
Drowsiness	Mild relaxation, can aid sleep.	Significant fatigue, lethargy, can impair daytime function.
Gastrointestinal	Minimal to no effect.	Increased risk of diarrhea, nausea, and vomiting.
Dry Mouth	May occur, but is typically mild.	More pronounced "cottonmouth" sensation.
Appetite	Minimal or subtle changes.	More noticeable changes, either increased or decreased.
Dizziness	Generally not an issue unless very sensitive.	Possible, due to temporary drop in blood pressure.
Anxiety	Can help reduce anxiety.	High doses can cause paradoxical increase in anxiety or irritability.
Liver Impact	Minimal risk for healthy individuals.	Potential for elevated liver enzymes, requires monitoring.

What to do if you've taken too much CBD

If you find yourself experiencing the uncomfortable effects of too much CBD, the first rule is not to panic, as severe outcomes are extremely rare. The effects are temporary and will fade as your body metabolizes the compound.

Stay Hydrated: Drink plenty of water to help with dry mouth and aid your body's metabolic process.
Eat a Snack: Having some food, particularly something light, can help stabilize your system and alleviate symptoms like dizziness or nausea.
Rest and Relax: Find a quiet, comfortable space to lie down. Napping can help pass the time and ease drowsiness. Deep breathing exercises can also help calm feelings of anxiety.
Seek Medical Advice if Needed: If symptoms are severe or persistent, or if you suspect an interaction with other medication, it is wise to consult a healthcare professional or contact a poison control center.

The importance of regulation and informed use

Ultimately, the risks associated with taking too much CBD are largely manageable and often relate to quality control issues in the largely unregulated market. By choosing high-quality, lab-tested products and starting with a low dose, users can effectively minimize potential side effects and find their optimal regimen. Understanding the difference between a mild, temporary reaction and a severe one is key to safe consumption.

Conclusion

While a fatal overdose from pure CBD is not a realistic concern, consuming an excessively high dose can lead to a variety of uncomfortable side effects, such as drowsiness, dry mouth, and digestive issues. The estimated toxic threshold is so high that most people would find it nearly impossible to reach. More significant risks involve potential interactions with other medications and possible liver enzyme abnormalities with long-term, high-dose use. Responsible usage—starting with a low dose from a reputable, lab-tested source and gradually increasing as needed—is the best way to avoid unwanted side effects and ensure a safe and beneficial experience with CBD. If you have any underlying health conditions or are taking other medications, consulting a healthcare professional is always the safest approach.

Frequently Asked Questions

No, a lethal overdose from pure CBD is not possible because it does not affect the brainstem areas that control respiratory function. Any adverse effects from consuming excessive amounts are typically mild and temporary.

The most common side effects of a high CBD dose include drowsiness, fatigue, dry mouth, nausea, diarrhea, and dizziness due to a temporary drop in blood pressure.

Yes, high doses of CBD can cause abnormalities in liver-related blood tests. The FDA has noted this risk, and it is particularly important for those with pre-existing liver conditions or who take other medications processed by the liver.

Yes, CBD can interact with a wide range of medications, including blood thinners, certain antidepressants, and anti-epileptic drugs. It inhibits a key liver enzyme (CYP450), which can alter the concentration of other drugs in your system.

There is no universal threshold, as it depends on individual factors. However, a clinical review found that doses up to 1,500 mg per day were generally well-tolerated in humans. The estimated toxic dose is significantly higher, at around 20,000 mg.

If you feel you have taken too much CBD, stay calm, as the effects are temporary. Drink water, eat a light snack, and rest in a quiet, comfortable place. If you have severe symptoms, contact a healthcare provider or a poison control center.

Start with a low dose and gradually increase it over time while observing your body's response. Buy products from reputable, third-party lab-tested sources to ensure accurate labeling and avoid contaminants.