6 Unexpected Side Effects Of Holy Basil

The effects of its overindulgence may not be so pretty.

Medically reviewed by Mary-Walker Hall, RDN Mary-Walker Hall Mary-Walker HallRDN facebook_icon
Written by , BSc, Professional Certificate in Food, Nutrition and Health Ravi Teja Tadimalla BSc, Professional Certificate in Food, Nutrition and Health linkedin_icon Experience: 8 years
Edited by , BA (Literature & Psychology), PG Diploma Arshiya Syeda BA (Literature & Psychology), PG Diploma linkedin_icon Experience: 7 years
Fact-checked by , BEd, MSc (Microbiology), Diploma In Nutrition Aparna Mallampalli BEd, MSc (Microbiology), Diploma In Nutrition linkedin_icon Experience: 5 years
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Several side effects of tulsi may make you think twice before using it. Tulsi or holy basil has a reputation for being a magical cure-all herb. This is no surprise given the variety of benefits it offers.

Tulsi is widely used in many home remedies. It is so well-known that even today, your elders might advise you to consume it for its health-promoting properties.

You can derive some amazing benefits from tulsi. Ayurveda recommends this herb for its health-boosting benefits. Tulsi, however, also has certain adverse effects you may have to deal with.

It could affect your fertility or affect the effectiveness of certain medications. As a result, you should understand tulsi’s potential side effects.

This article examines the side effects of tulsi, its safety, and any potential drug interactions. Read on.

protip_icon Know The Flip Side: Tulsi

Short-Term Effects
Can cause rapid breathing, heartburn, nausea, diarrhea, dizziness, and bruising.

Long-Term Effects
Can cause liver toxicity, acute kidney injury, increased uterine contractions in pregnant persons, and complications during childbirth or menstruation.

Drug Interactions
Tulsi interferes with blood-thinning and diabetes medications and may reduce the effects of anti-anxiety and anticholinergic medicines.

When To See A Doctor
If you experience excessive or prolonged intervals of bleeding, hypoglycemia, coughing bloody mucus, and notice blood in the urine, seek immediate help.

6 Top Holy Basil Side Effects

Let’s have a look at the unexpected side effects of Tulsi leaves:

1. Eugenol Overdose

Woman having poisining effect from tulsi leaves
Image: Shutterstock


Eugenol is the primary constituent of Tulsi.


It was found that excess consumption of Tulsi can lead to eugenol overdose (1). There is a possibility to consume too much of eugenol that might even lead to poisoning (2).

Eugenol is found in clove cigarettes and some food flavoring.


Bleeding during coughs, rapid breathing and blood in urine.

protip_icon Did You Know?
You may also experience liver toxicity, nausea, diarrhea, dizziness, or acute kidney injury due to a eugenol overdose (11).

2. Blood Thinning


Tulsi has the property to thin the blood in our bodies. And hence it should not be taken along with other anti-clottingi  A substance, property, or drug that slows down or prevents the process of clotting in the body. medications (3).


People who already are taking blood-thinning medications like warfarin and heparin should restrict the consumption of Tulsi. Tulsi can intensify the blood thinning properties of the prescribed drugs and lead to more severe complications. It also can increase blood clotting time and inhibit platelet aggregation (4). It is not good for people who suffer from bleeding disorders.


Bruising and/or prolonged periods of bleeding.

3. Hypoglycemia

Woman having low blood sugar level due to side effect of tulsi
Image: Shutterstock


Hypoglycemiai  A condition when the blood sugar level is below the normal range and causes symptoms like anxiety and heart palpitations. is a condition of abnormally low blood sugar. Though it is not a disease, it can be a sign of health problem (5).


Tulsi is taken by people with high blood sugar to lower their blood sugar levels. But if people who have diabetes or hypoglycemia and are under medication consume Tulsi, it might lead to excessive reduction in blood sugar. This is one of the most dangerous side effects of Tulsi that one should be aware of.


Paleness, dizziness, hunger, weakness, irritability (6).

4. Might Impact Fertility

Excess tulsi consumption leads to infertility issues
Image: Shutterstock


Tulsi might cause infertility in males.


Tests were conducted on male rabbits. The rabbits were divided into test and normal groups. Test group rabbits were two grams of Tulsi leaves for over a period of 30 days. A significant decrease in the sperm count of test group rabbits was noted (7).

5. Reactions In Pregnant Women

Pregnant woman experiencing side effect of excess tulsi consumption
Image: Shutterstock


Excessive consumption of Tulsi by pregnant women may have long term effects both on the mother and the baby. Tulsi might also trigger reactions in pregnant women.


One of the holy basil side effects also include increase in uterine contractions in pregnant women (8). This side effect of Tulsi can lead to complications during childbirth or menstruation.


Backache, cramps, diarrhea and bleeding (9).

6. Drug Interactions

Woman feeling nauseated due to a drug interaction by tulsi
Image: Shutterstock


Tulsi might interfere with the way how our body processes certain drugs.


This is done by using ‘cytochrome P450i  Proteins found in animal and plant tissues that help in the formation of energy and metabolism of drugs. ’ – the liver’s enzyme system. As a result of this, the levels of drugs in the blood might increase or decrease.

Diazepam and scopolamine are two drugs which help reduce nausea, vomiting and nervousness, anxiety respectively. Tulsi might reduce the amnesic effect caused by these two drugs (10).


Heartburn, light-headedness, headache and nausea.

protip_icon Quick Tip
It is recommended not to chew tulsi leaves because their mercury content and acidic nature can discolor your teeth.

Any substance, however natural it is, has side effects. It might come as a cure for a certain disease. Or it might possess very good healing properties. But that doesn’t make it devoid from side effects.

Infographic: Top 3 Side Effects Of Holy Basil (Tulsi)

Tulsi is used to treat various infections, skin conditions, and other health conditions. But did you realize that it may have several adverse effects as well? Although it has been a staple of Ayurvedic and Chinese medicine for millennia, excessive use can have harmful side effects. See the infographic below to find out more about them.

top 3 side effects of holy basil(tulsi) (infographic)

Illustration: StyleCraze Design Team

Tulsi is an aromatic herb commonly used in many home remedies for treating a variety of ailments. However, overconsumption can lead to a number of problems. The side effects of tulsi range from affecting fertility to possibly lowering blood sugar levels and liver damage. There is a possibility of eugenol poisoning where your urine and cough may contain blood. In some cases, tulsi may trigger allergic reactions or interfere with the functioning of certain medications, especially blood thinners, diazepam, and scopolamine. If possible, try to limit your intake or stay away from it entirely to avoid such complications.

Frequently Asked Questions

Can tulsi be taken daily?

Yes. It is safe to have 2-3 leaves of tulsi every day. However, excess consumption may prove to be harmful.

Is chewing tulsi harmful?

No. Scientific evidence does not support the claim that chewing tulsi can cause harm.

What precautions should one take before consuming tulsi to avoid any side effects?

You could start by consuming small amounts of tulsi every day, checking your blood sugar levels and for signs of any allergic reaction. Avoid consuming it before any surgery or if you are pregnant or lactating.

How much tulsi is too much?

There is no common consensus on which amount of tulsi would be considered to be too much. You can limit yourself to 1-2 tablespoons of the herb daily. Your health status also plays an important factor and hence speak with your healthcare provider to determine how much would be excessive for you.

Can we eat tulsi on an empty stomach?

Yes. According to anecdotal evidence, chewing a couple of tulsi leaves or having its tea on an empty stomach can help boost your overall well-being.

Can tulsi cause any hormonal imbalances?

Possibly. A study conducted on male albino rabbits showed that consumption of 2g fresh tulsi levels led to lowered levels of follicle-stimulating hormone and luteinizing hormone, and an increase in testosterone levels. It also reduced sperm count (7).

Can tulsi interact with alcohol or recreational drugs?

Possibly. There is a lack of studies on the interaction of tulsi herb with alcohol or other recreational drugs. However, since tulsi does have other notable herb-drug interactions, it is recommended to use caution.

Can tulsi affect the absorption of nutrients from other foods?

Yes, positively. A study showed that tulsi may boost digestion and enhance the absorption and use of nutrients obtained from other foods (11).

Key Takeaways

  • Animal studies suggest holy basil may decrease sperm count.
  • Pregnant women should avoid consuming Tulsi as it may lead to uterine contractions.
  • Tulsi can negatively interact with medications like blood thinners and cause severe health damage.
  • People with diabetes should practice caution while using holy basil as it may lower blood sugar levels.
side effects of tulsi_illustration

Image: Stable Diffusion/StyleCraze Design Team

Holy basil has many health benefits, but it can also have some side effects. Click on the video below to know about the potential risks and how to stay safe.

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Mary-Walker Hall
Mary-Walker HallBS (Food, Nutrition, & Dietetics)
Mary-Walker Hall is a Registered Dietitian Nutritionist with 12 years of experience, who has a passion for equipping parents and caregivers with the tools to raise healthy eaters from the start. She focuses on whole foods and an overall healthy lifestyle with simple strategies, such as baby-led weaning.

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