Fennel Benefits and Side Effects

Published on Nov 17, 2023 by


Fennel is used as a culinary herb and medicinal plant for centuries. There is promising evidence that it can treat various conditions, from inflammation and pain to digestive issues and depression. However, its regular usage should be avoided due to the potential for severe adverse effects. Find out all you need to know about the potential advantages to your health and any serious risks you should be aware of before consuming this plant.

What is fennel?


Fennel is a plant originally from the Mediterranean but is now cultivated in many different parts of the world and has various purposes.

Fennel, a fragrant herb with a pleasant flavor, is utilised in various ways.

  • as a spice
  • eaten raw
  • dried
  • braised
  • grilled
  • shaved
  • stewed

It is a common ingredient in salads, sausages, ice cream, pastries, alcoholic beverages, pasta meals, and more. It has a characteristic liquorice-like flavour.

Benefits of fennel


Young children who scream or seem distressed for extended periods each day are said to have “colic” for this condition. What causes this is a mystery, but digestive problems and stomach cramps are likely contributors.

Babies with infantile colic can benefit from fennel (either as an oil, a tea, or a herbal substance), according to a meta-analysis and assessment of 14 clinical trials of supplements for digestive problems.

Fennel seed oil effectively treated colic in 65% of newborns in research, including 125 babies, while just 24% of babies in the placebo group showed any improvement.

Improving Stomach/Gut Discomfort


Stomach aches, flatulence, diarrhoea, and constipation are just a few of the gut and digestive issues traditionally treated with fennel. But now, there needs to be more proof to back up these advantages.

In research involving 121 IBS patients, a blend of fennel and curcumin essential oils reduced stomach pain and enhanced quality of life. Through alcohol-induced stomach ulcers were avoided by fennel extract.

It is insufficient to conclude that fennel reduces gastrointestinal discomfort based on a tiny study that combined it with curcumin and a few animal trials. Larger, more carefully planned clinical trials are required to clarify any potential advantages of gut health.

Alleviating Menstrual Pain


A study involving 30 women who experienced exceptionally painful periods revealed that fennel helped relieve their discomfort (dysmenorrhea). There was a delay of 30 minutes to 120 minutes before this impact became noticeable. Only one participant noticed a slight increase in menstrual flow. In a study involving 68 female college students, the combination of fennel extract and vitamin E was found to be more efficient than ibuprofen in reducing the intensity of menstruation discomfort.

Fennel tablets were more effective than a placebo at reducing nausea and improving mood in a trial of 80 young women experiencing their period. However, few studies and those that exist are often of poor quality. Fennel may help reduce menstruation pain, but this needs to be tested in larger studies.

Reducing Menopause Symptoms

Reducing Menopause

Hot flashes, sweating, heart discomfort, sleep issues, sadness, irritability, exhaustion, anxiety, sexual dysfunction, and joint and muscle pain are all common menopause symptoms.

Fennel successfully alleviated menopausal symptoms in a placebo-controlled, double-blind study involving 90 women.

Though fennel has shown promise in easing menopausal symptoms, more research is needed to validate its efficacy.

Unwanted Hair Growth in Women

Unwanted Hair Growth in Women

Unwanted hair growth, or hirsutism, can affect even women with regular menstrual cycles and normal levels of male hormones (for example, inappropriate facial hair growth).

Although the root reasons for this unpleasant ailment are unknown, fennel has shown promise in reversing it.

In a randomised controlled trial (DB-RCT) with 44 women and another study with 38 women, fennel gels and creams diminished hair growth and thickness when applied directly to the skin. However, larger, better-designed studies are needed to prove that fennel is helpful for this illness.

Anxiety and Depression

Anxiety and Depression

Sixty postmenopausal women participated in a randomised controlled trial (DB-RCT) and found that fennel was marginally effective in relieving their anxiety and sadness.

Reducing Appetite

Fennel tea reduced appetite and improved satiety in 9 healthy, overweight women.

Improving Skin Health

Improve skin

Eleven volunteers saw an improvement in skin texture and an increase in skin water content after using a fennel extract cream. Fennel extract can delay or even prevent sun damage to the skin. It upregulated Nrf2 and antioxidants like GSH, which led to a dose-dependent reduction in reactive oxygen species (ROS) generation.

According to research, Fennel and trans-anethole can bleach the skin and may prevent skin blemishes by obstructing the synthesis of melanin in response to ultraviolet light (melanogenesis).

Side Effects of fennel 

side effects of fennel

Although some people may be allergic to fennel, it is generally considered quite minor. It is also harmful to consume excessive oils derived from fennel.

The effects of oestrogen have been studied and shown to be mimicked by fennel. Do not consume fennel tea if you are pregnant or nursing. In addition, people with estrogen-sensitive tumours should stay away from fennel.

Since estragole, an essential component of fennel, has been labelled as a possible carcinogen, people with cancer or those at high risk for the disease are advised to minimise their consumption of fennel tea, if not completely avoid it.


fennel dosage

Fennel has not been approved by the Food and Drug Administration (FDA) for the treatment of any medical condition, hence there is no standard dosage. The supplement industry and its consumers have developed their unofficial dosage guidelines. If you think fennel would be helpful as a supplemental treatment for your condition, talk to your doctor about how much you should take.

Most clinical trials used 100 mg of active components per capsule of fennel, taken twice or thrice daily.

Taken as a tea, this herb is typically used 30 minutes before a meal (to aid with digestion) and up to three times a day for additional uses. The seeds of the fennel plant are very frequently used in the kitchen.



The negative effects of fennel have been studied and found to be minimal. Even though fennel may have some positive effects when used in moderation or for a short period, it is best to avoid using it regularly because the anethole it contains is a potent oestrogen mimic. It is also safe for newborns; however, its usage is typically limited to brief intervals.

Special Precautions


When taken by mouth: 

taken by mouth

Many dishes feature fennel. It may be safe when used medicinally in suitable doses and for a limited duration. The long-term safety of fennel use is uncertain because of a lack of sufficient data. Seizures and stomach discomfort are possible, although they are infrequent, side effects.

When applied to the skin: 

When applied to the skin

Potentially, fennel is safe to eat. Skin exposed to fennel may become more photosensitive and burn more easily. You should protect your fair skin by using sunscreen. Possible dangers to the unborn child from consuming fennel. Premature birth has been connected to the use of fennel regularly.



There is concern that fennel might be toxic. Breastfed infants have been reported to suffer neurological harm from exposure to fennel in herbal tea through breastfeeding.



Using proper amounts of fennel in newborns with colic may be safe for up to a week.

Allergy to celery, carrot, or mugwort: 


Individuals with a sensitivity to fennel may experience an allergic reaction.

Bleeding disorders: 

Bleeding disorders

Fennel has anticoagulant properties. People with bleeding disorders should avoid taking fennel because it may increase their risk of bleeding and bruising. Fennel may have estrogenic effects, which could help with hormone-sensitive conditions like breast cancer, uterine cancer, ovarian cancer, endometriosis, and uterine fibroids. Fennel should be avoided by anyone with the condition that could be exacerbated by oestrogen.


What is fennel?

You can eat the fennel plant’s seeds, leaves, and fruits. The use of fennel seeds has spread globally.

What are the uses of fennel seeds?

You can use fennel tea as a breath mint. Fennel tea and fennel water are also tasty options.

What are the benefits of fennel tea?

Regular consumption of fennel tea has been linked to evidence of a diuretic effect, which could aid in removing accumulated fluid in the body. Fennel tea may have carminative effects, too. Potentially useful for alleviating bloating and gas. If you’re thinking about drinking fennel tea for its health advantages, or any other kind of herbal tea, you should first talk to your doctor.

What is fennel water used for?

To alleviate baby flatulence (gas buildup), a fennel seed concoction known as “gripe water” is given to the child. Fennel water can help with bloating and gas. However, any herbal medicine should be preceded by a discussion with a medical professional.


Foeniculum vulgare is the scientific name for fennel. It has a lengthy history of usage as a medication in both traditional Chinese medicine and Ayurvedic practice. The fennel plant is edible from the root through fronds to seeds. Eat it raw in a salad, saute it in butter or good oil, or roast it.

Research has shown that fennel can help with various health issues, including improving cardiovascular health; enhancing skin health; facilitating digestion; increasing satiety; relieving colic in infants; preventing cancer; enhancing eye health, and alleviating menopausal symptoms.

About the Author: John Falcone

John Falcone is an esteemed tech journalist and editor, known for his extensive knowledge and insightful commentary on consumer electronics. With a career marked by in-depth reviews, analysis, and reporting, John has established himself as a go-to expert in the field of technology. His articles often delve into the intricacies of the latest gadgets, offering readers clear, concise, and informative perspectives. John's ability to demystify complex technical topics and trends has earned him a loyal readership and respect among tech enthusiasts. His work is characterized by meticulous research, a keen understanding of consumer needs, and an ability to predict industry directions.

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