Toxicity of fennel

Dangers of fennel remedies

Can fennel be toxic?

Fennel (Foeniculum vulgare), in normal food uses, is not toxic. Nor does it present toxicity in suitable medicinal uses.

On the other hand, a number of possible side effects and contraindications have to be taken into account, especially in sensitive people, such as children and pregnant women and during breastfeeding.

Dangers of fennel essential oil

Fennel drawing

The greatest danger of this plant lies in the use of its essential oil or of highly concentrated remedies with fennel fruits.

Fennel essential oil is extremely toxic (neurotoxic) and for this reason its ingestion is not recommended. Even diluted, it has toxicity and should not be taken without the advice of the doctor.

Dangers of remedies heavily loaded with fennel

Likewise, fennel fruits can be toxic when taken in high quantities.

For example, there have been cases of intoxication in infants, whose mothers took infusions heavily loaded with fennel and anise (two plants with much anethole, component of their essential oil).

Why is fennel essential oil toxic?

The essential oil, which is extracted from its fruits, is toxic because it has a series of components with toxic properties. Among them, the most important are:

  • Anethole
  • Estragol

What symptoms does poisoning with fennel essential oil show?

dried fennel fruits
Fennel fruits, the richest part of the plant in essential oils

The undiluted fennel essential oil is very toxic, since only doses greater than 1 ml can affect the nervous system. Among the main symptoms that can cause poisoning by fennel essential oil we have the following:

  • Tremors
  • Seizures
  • Drowsiness
  • Hallucinations
  • Muscle weakness and lethargy
  • Respiratory problems
  • Edema in the lungs

Fennel fruits (seeds) , when taken in high quantities, can produce similar results.

punto rojo More information on fennel


This article was endorsed by Elisenda Carballido - Dietitian nutritionist. Postgraduate in Phytotherapy and master in Nutrition and Metabolism.
Written by Editorial Botanical-online team in charge of content writing

29 October, 2019

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