Reviewed on 6/11/2021
Other Name(s):

Berce Commune, Berce Laineuse, Berce Très Grande, Cow Cabbage, Cow Parsnip, Heracleum lanatum, Heracleum maximum, Heracleum montanum, Heracleum sphondylium, Heracleum sphondylium subsp. montanum, Hogweed, Imperatoria, Madnep, Radix Pimpinelle Franconiae, Woolly Parsnip, Youthwort.


Masterwort is a plant. People use it to make medicine.

Despite safety concerns, people take masterwort for relief of muscle cramps, stomach disorders, digestive problems, diarrhea, and swelling of the tissue that lines the stomach and intestines.

There have been some reports that masterwort is used as a replacement to “stretch” greater burnet-saxifrage (Pimpinella major) products.

How does it work?

There is not enough information to know how masterwort might work.


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Uses & Effectiveness

Insufficient Evidence to Rate Effectiveness for...

  • Muscle cramps.
  • Stomach disorders.
  • Digestion problems.
  • Diarrhea.
  • Swelling (inflammation) of the lining of the stomach and intestines.
  • Other conditions.
More evidence is needed to rate the effectiveness of masterwort 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

Masterwort is POSSIBLY UNSAFE when taken by mouth or applied to the skin. It can cause the skin to burn more easily in the sun. Wear protective clothing and sunblock outside, especially if you are light-skinned. Also, there are some chemicals in masterwort that can cause cancer.


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Special Precautions & Warnings

Pregnancy and breast-feeding:If you are pregnant, it's LIKELY UNSAFE to take masterwort by mouth, especially in early pregnancy. It might start your menstrual period, and that could cause a miscarriage.

It is POSSIBLY UNSAFE to take masterwort by mouth if you are breast-feeding. It's best to avoid use.

Exposure to ultraviolet (UV) light including sunlamp treatment for certain skin conditions such as psoriasis, use of tanning beds, or time in sunlight: Masterwort causes sensitivity to ultraviolet (UV) light. It could cause your skin to burn. Don't use masterwort if you are receiving UV light therapy. Also, stay out of the sun and avoid tanning beds if you are taking masterwort.


Medications that increase sensitivity to sunlight (Photosensitizing drugs)Interaction Rating: Moderate Be cautious with this combination.Talk with your health provider.

Some medications can increase sensitivity to sunlight. Masterwort might also increase your sensitivity to sunlight. Taking masterwort along with medication that increase sensitivity to sunlight could increase the chances of sunburn, blistering, or rashes on areas of skin exposed to sunlight. Be sure to wear sunblock and protective clothing when spending time in the sun.

Some drugs that cause photosensitivity include amitriptyline (Elavil), Ciprofloxacin (Cipro), norfloxacin (Noroxin), lomefloxacin (Maxaquin), ofloxacin (Floxin), levofloxacin (Levaquin), sparfloxacin (Zagam), gatifloxacin (Tequin), moxifloxacin (Avelox), trimethoprim/sulfamethoxazole (Septra), tetracycline, methoxsalen (8-methoxypsoralen, 8-MOP, Oxsoralen), and Trioxsalen (Trisoralen).


The appropriate dose of masterwort 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 masterwort. 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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Kriazheva, S. S., Khamaganova, I. V., and Kolibrina, A. M. [Dermatitis bullosa in children caused by cow-parsnip]. Pediatriia. 1991;(6):88-90. View abstract.

Maksakova, G. P. [Case of contact dermatitis caused by Sosnovskii's cow parsnip]. Vestn.Dermatol Venerol. 1978;(8):48-49. View abstract.

Prinz, V. L. and Kostler, H. [Report on 3 cases of toxic phytophotodermatitis due to Heracleum mantegazzianum (giant cow parsnip)]. Dermatol Monatsschr. 1976;162(11):881-886. View abstract.

Rogov, V. D. [Acute bullous dermatitis developing after contact with cow parsnip (Heracleum)]. Vestn.Dermatol Venerol. 1985;(11):58-59. View abstract.

Sokolova, E. M. [Bullous occupational dermatitis caused by the cow parsnip]. Vestn.Dermatol Venerol. 1968;42(2):64-67. View abstract.

Ippen H. [Phytophotodermatitis caused by plant trimming (edger's rash)]. Derm Beruf Umwelt 1990;38:190-2. View abstract.