Male Fern

Other Name(s):

American Aspidium, Bear's Paw, Dryoptère Fougère Mâle, Dryopteris filix-mas, European Aspidium, Fougère Mâle, Helecho Macho, Knotty Brake, Marginal Fern, Shield Fern.


Male fern is a very poisonous plant. Taking it by mouth can cause death. Despite these serious safety concerns, some people use the leaf and other parts that grow above the ground, as well as the underground stem (rhizome), to make medicine.

Male fern is used to treat nosebleeds, heavy menstrual bleeding, wounds, and tumors. It is also used to expel worms, typically tapeworms, from the intestines.

Some veterinarians use male fern to treat worms in animals.

How does it work?

Male fern contains chemicals that can kill intestinal worms such as tapeworms. Once the worms have been killed, salt water (saline) is taken to flush them from the body.


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Uses & Effectiveness

Insufficient Evidence to Rate Effectiveness for...

  • Nosebleeds.
  • Heavy menstrual bleeding.
  • Wounds.
  • Tumor.
  • Tapeworms.
  • Other conditions.
More evidence is needed to rate the effectiveness of male fern for these uses.

Natural Medicines Comprehensive Database rates effectiveness based on scientific evidence according to the following scale: Effective, Likely Effective, Possibly Effective, Possibly Ineffective, Likely Ineffective, and Insufficient Evidence to Rate (detailed description of each of the ratings).

Side Effects

Male fern is UNSAFE. It is a violent poison and should not be taken by mouth. In fact, Canada requires that male fern products be labeled “For external use only.” Since there are other products available that are effective and safer than male fern, there is no reason to use it.

Side effects caused by taking male fern can be serious and include breathing difficulty, nausea, diarrhea, dizziness, headaches, tremors, convulsions, heart and lung failure, eye disorders, muscular weakness, coma, temporary or permanent blindness, and death.

Treatment of overdose consists of giving salt water followed by other special fluids. It is important to avoid fats and oils because they increase the amount of male fern that is absorbed by the body. If seizures occur, benzodiazepines may be used, and a breathing machine may be necessary.


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Special Precautions & Warnings

Male fern shouldn't be used by anyone. Some people may be at even higher risk of side effects.

Pregnancy and breast-feeding: Male fern is UNSAFE for anyone to take as medicine. If you take it while pregnant or breast-feeding, you will endanger yourself as well as your baby.

Stomach and intestinal conditions: Stomach and intestinal conditions that increase digestion time might increase the amount of male fern that is absorbed in the intestine. This bigger dose of male fern could lead to more serious side effects.


The appropriate dose of male fern depends on several factors such as the user's age, health, and several other conditions. At this time there is not enough scientific information to determine an appropriate range of doses for male fern. Keep in mind that natural products are not always necessarily safe and dosages can be important. Be sure to follow relevant directions on product labels and consult your pharmacist or physician or other healthcare professional before using.

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Report Problems to the Food and Drug Administration

You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.


Fetrow CW, Avila JR. Professional's Handbook of Complementary & Alternative Medicines. 1st ed. Springhouse, PA: Springhouse Corp., 1999.

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