What medications does chamomile interact with?

October 10, 2025 •

4 min read

Over one million cups of chamomile tea are consumed daily for relaxation, but this common herb can interact with several prescription drugs [1.2.3]. Understanding what medications chamomile interacts with is crucial for avoiding potentially harmful side effects, from excessive bleeding to increased sedation [1.2.2, 1.3.6].

Quick Summary

Chamomile can interact with blood thinners like warfarin, sedatives including benzodiazepines, certain diabetes and blood pressure drugs, and hormone therapies such as tamoxifen. It also affects liver enzymes, altering how many medications are metabolized.

Key Points

Blood Thinner Interaction: Chamomile contains coumarins and can significantly increase the risk of bleeding when taken with anticoagulants like warfarin [1.2.1, 1.2.3].
Sedative Effects: It can enhance the effects of CNS depressants like benzodiazepines and alcohol, leading to excessive drowsiness [1.5.3].
Liver Enzyme Inhibition: Chamomile inhibits Cytochrome P450 enzymes (CYP1A2, CYP2C9, CYP3A4), which can alter the levels of many medications in the body [1.7.2].
Diabetes Medication Caution: It may lower blood sugar, creating a risk of hypoglycemia for individuals taking insulin or other diabetes drugs [1.6.2].
Hormone Therapy Interference: Chamomile might interfere with hormone treatments like tamoxifen and birth control pills due to potential estrogenic effects and enzyme inhibition [1.3.2, 1.8.3].
Consult Professionals: Always talk to a healthcare provider before using chamomile supplements if you take any prescription medications [1.2.2].
Surgery Risk: You should stop taking chamomile at least two weeks before any scheduled surgery to reduce the risk of bleeding [1.4.4].

The Hidden Risks of a Common Herbal Remedy

Chamomile, available as German chamomile (Matricaria recutita) and Roman chamomile (Chamaemelum nobile), is one of the most popular herbal supplements, widely consumed in teas for its calming effects and to aid with sleep [1.2.3]. While the U.S. Food and Drug Administration (FDA) lists it as "Generally Recognized As Safe" (GRAS), this designation applies to its use in food, not as a medicinal supplement [1.2.3]. When consumed in larger, concentrated doses, chamomile can have significant pharmacological effects and interact with a range of conventional medications [1.2.2]. These interactions can alter a drug's efficacy or increase the risk of adverse effects. Among patients taking prescription medications, an estimated 20% to 25% also use a dietary supplement, often without informing their doctor, creating a risk for unintended interactions [1.9.1, 1.9.3].

How Chamomile Causes Drug Interactions

The primary mechanisms behind chamomile's interactions involve its inherent properties and its effect on the body's drug-metabolizing systems.

Additive Sedative Effects

A well-known benefit of chamomile is its mild sedative effect, which helps promote relaxation and sleep [1.2.4]. This is due to a flavonoid called apigenin, which can bind to benzodiazepine receptors in the brain [1.2.6]. When taken with other central nervous system (CNS) depressants—such as prescription sedatives, anti-anxiety medications, or alcohol—this effect can become additive. The combination can lead to excessive drowsiness, dizziness, and impaired coordination, making activities like driving dangerous [1.5.1, 1.5.2, 1.5.4].

Increased Bleeding Risk

German chamomile contains natural compounds called coumarins, which have mild anticoagulant (blood-thinning) properties [1.2.1, 1.2.3]. While these compounds in chamomile are not as potent as the prescription drug warfarin (which is also a coumarin derivative), they can enhance the effects of other anticoagulant and antiplatelet drugs [1.4.1]. This synergy increases the risk of bruising and serious bleeding events. There is a documented case of a patient on warfarin who experienced severe internal hemorrhaging after consuming large amounts of chamomile tea and using a chamomile lotion [1.2.1, 1.4.1]. Caution is therefore advised when combining chamomile with drugs like warfarin, aspirin, and clopidogrel [1.2.5, 1.3.6].

Interference with Liver Enzymes (Cytochrome P450)

Perhaps the most significant and wide-reaching interaction involves chamomile's effect on the Cytochrome P450 (CYP450) enzyme system in the liver [1.2.6]. This enzyme family is responsible for metabolizing a vast number of prescription drugs. In-vitro studies have shown that chamomile can inhibit several key CYP enzymes, including CYP1A2, CYP2C9, CYP2D6, and CYP3A4 [1.7.1, 1.7.2]. By inhibiting these enzymes, chamomile can slow the breakdown of other drugs, causing their levels in the blood to rise, potentially to toxic levels [1.7.4]. For example, concurrent use with the immunosuppressant cyclosporine has led to increased serum levels of the drug [1.2.6]. This mechanism means chamomile could theoretically interact with hundreds of medications.

Major Medication Classes That Interact with Chamomile

Given these mechanisms, several classes of medications require particular caution.

Anticoagulants and Antiplatelet Drugs

Due to its coumarin content, chamomile can potentiate the effects of blood thinners, increasing bleeding risk [1.2.3].

Examples: Warfarin (Coumadin), clopidogrel (Plavix), aspirin, and NSAIDs like ibuprofen and naproxen [1.2.5, 1.3.6].
Effect: Increased risk of bruising, bleeding gums, and internal hemorrhage [1.4.3].

Sedatives and CNS Depressants

The natural sedative properties of chamomile can have an additive effect with other depressants [1.3.2].

Examples: Benzodiazepines (e.g., lorazepam/Ativan, alprazolam/Xanax), barbiturates, some antidepressants, anti-seizure medications, and alcohol [1.3.6, 1.5.3].
Effect: Excessive drowsiness, dizziness, and respiratory depression [1.5.3, 1.7.4].

Diabetes Medications

Some studies suggest chamomile can lower blood sugar levels [1.6.4, 1.6.5]. While this may be beneficial, combining it with diabetes medications can increase the risk of hypoglycemia (dangerously low blood sugar) [1.6.2].

Examples: Insulin, metformin, glyburide.
Effect: Enhanced blood sugar-lowering effect, potentially leading to hypoglycemia.

Hormone Therapies

Chamomile may have weak estrogenic effects, which could interfere with hormone-sensitive treatments [1.2.2].

Example: Tamoxifen (used for breast cancer) [1.8.3].
Effect: Chamomile's inhibition of CYP2D6 and CYP3A4 could theoretically reduce the conversion of tamoxifen to its active form, potentially decreasing its effectiveness [1.8.1, 1.8.2]. It could also interfere with estrogen-containing oral contraceptives [1.3.2].

Chamomile Drug Interaction Comparison Table


Drug Class	Example Medications	Potential Interaction & Effect	Risk Level
Anticoagulants/Antiplatelets	Warfarin, Aspirin, Clopidogrel	Contains coumarins that enhance blood-thinning effects [1.2.1].	High
Sedatives (CNS Depressants)	Benzodiazepines (Lorazepam), Barbiturates, Alcohol	Additive sedative effects leading to excessive drowsiness [1.5.3].	Moderate to High
CYP450 Substrates	Cyclosporine, Statins, many others	Inhibits liver enzymes, increasing drug concentrations and risk of toxicity [1.7.2].	Moderate
Diabetes Medications	Metformin, Insulin	May lower blood sugar, increasing the risk of hypoglycemia when combined [1.6.2].	Moderate
Hormone Therapies	Tamoxifen, Birth Control Pills	May interfere with estrogen-sensitive drugs or reduce their effectiveness [1.3.4, 1.8.3].	Low to Moderate

Conclusion: Always Consult a Healthcare Provider

While chamomile is a gentle and widely used herbal product, it is not without risks. Its ability to interact with common and critical medications—especially blood thinners, sedatives, and drugs metabolized by the liver—highlights the importance of caution. The clinical significance of some interactions, particularly those involving CYP450 enzymes, is still being studied, but the potential for harm exists [1.7.2]. Before adding chamomile supplements or consuming large quantities of chamomile tea to your routine, it is essential to discuss it with your doctor or pharmacist. This is especially critical if you take any prescription medications, are pregnant or breastfeeding, or are scheduled for surgery [1.2.2, 1.4.4].

For more information on chamomile and its safety, you can visit the National Center for Complementary and Integrative Health (NCCIH).

Frequently Asked Questions

It is not recommended to consume large amounts of chamomile tea while taking warfarin. Chamomile contains compounds that can enhance warfarin's blood-thinning effect, significantly increasing your risk of bleeding [1.4.3]. A case has been reported of severe internal bleeding from this combination [1.4.1].

You should be cautious. Chamomile has sedative properties that can add to the effects of many antidepressants and anti-anxiety medications, such as benzodiazepines. This can cause excessive sleepiness [1.5.3, 1.3.6]. Consult your doctor before combining them.

Yes, there is a potential for interaction. Since chamomile may have a mild blood pressure-lowering effect, taking it with prescribed antihypertensive drugs could cause your blood pressure to drop too low (hypotension). Discuss this with your healthcare provider.

Chamomile can inhibit several key liver enzymes in the Cytochrome P450 family (like CYP3A4, CYP1A2, and CYP2C9) [1.7.2]. These enzymes break down many common drugs. By inhibiting them, chamomile can cause these drugs to build up in your system, increasing the risk of side effects and toxicity [1.7.4].

There is no strong evidence of a major interaction between standard doses of chamomile and Tylenol. However, because chamomile can affect liver enzymes, and high doses of acetaminophen can also stress the liver, it is always best to consult a healthcare professional.

Some preliminary evidence suggests that chamomile might have weak estrogen-like effects and could potentially decrease the effectiveness of birth control pills [1.2.2, 1.3.4]. It's recommended to use an additional form of birth control, like a condom, if you take them together [1.7.4].

It is generally recommended to stop taking chamomile supplements or high doses of chamomile tea at least two weeks before a scheduled surgery. This helps to minimize the risk of increased bleeding during and after the procedure [1.4.4].