Horny Goat Weed
OTHER NAME(S): barrenwort, Bishop’s hat, Epimedium species, herba epimedii, horny goat weed, yin yang huo
Overview
Horny goat weed is a type of plant. It is available over the counter as a dietary supplement, usually as a tablet or capsule. People take horny goat weed for many different reasons, although its benefits are not well defined. Common side effects may include dry mouth, nausea, upset stomach, or vertigo (feeling off balance or like you or your surroundings are spinning). Before taking horny goat weed, make sure to tell your health care provider about any health conditions you have or medicines you are taking.
Uses
What is horny goat weed used for?
Horny goat weed is a plant used for many different reasons. However, the benefits of horny goat weed are not well defined. Some common reasons that people use horny goat weed include the following.
- Erectile dysfunction, a condition where you have trouble getting or keeping an erection
- Osteoporosis
- To increase sex drive in men
- To improve mental and physical performance
Note: The FDA has not reviewed horny goat weed for safety and effectiveness. Learn more about dietary supplements here.
How does horny goat weed work (mechanism of action)?
Dietary supplements made from horny goat weed contain plants that belong in the Epimedium genus. These products usually contain the leaves and stems of the plant. In traditional Chinese medicine, horny goat weed products are most often made from E. brevicornum and E. koreanum and are known as yin yang huo (yinyanghuo). Some people also refer to horny goat weed as barrenwort or Bishop’s hat.
Horny goat weed contains many different chemicals that have effects in the body, including flavonoids and icariin. These chemicals may help to relax blood vessels, which can increase blood flow to different parts of the body. When blood flow to the penis is increased, this is thought to help improve sexual function and help with erectile dysfunction. When blood flow to the brain is increased, this is thought to improve brain function and increase energy levels. But the benefits of horny goat weed for these uses are not well defined.
The chemicals in horny goat weed may also change the way that the body responds to certain hormones, including testosterone and estrogen. This may help to reduce bone loss in women who have osteoporosis. But the benefits of horny goat weed for this use are not well defined.
Herbal products like horny goat weed naturally contain many different chemicals. The amounts of each chemical in a specific product may vary. Different amounts may change the effects of horny goat weed on the body. Some horny goat weed dietary supplements are made to contain a certain amount of these substances. For example, products that are marketed to men are often made from E. sagittatum and are made to contain a certain amount of icariin.
How should I store horny goat weed?
You should store horny goat weed according to the product label. Most dietary supplements should be kept in a cool, dry location that is out of the reach of children and pets and not in direct sunlight.
Side Effects
What are the most common side effects of horny goat weed?
The most common side effects of horny goat weed are listed below. These side effects may vary depending on the dose you are taking or the specific product you are using. Tell your health care provider if you have any of these side effects that bother you.
- Dry mouth
- Nausea
- Upset stomach
- Vertigo
There may be other side effects of horny goat weed that are not listed here. Contact your health care provider if you think you are having a side effect of a supplement. In the U.S., you can report side effects to the FDA at www.safetyreporting.hhs.gov or by calling 888-SAFEFOOD (888-723-3366). In Canada, you can report side effects to Health Canada at www.health.gc.ca/medeffect or by calling 866-234-2345.
What are the serious side effects of horny goat weed?
While less common, the most serious side effects of horny goat weed are described below, along with what to do if they happen.
Severe Allergic Reactions. Horny goat weed may cause allergic reactions, which can be serious. Stop taking horny goat weed and get help right away if you have any of the following symptoms of a serious allergic reaction.
- Breathing problems or wheezing
- Racing heart
- Fever or general ill feeling
- Swollen lymph nodes
- Swelling of the face, lips, mouth, tongue, or throat
- Trouble swallowing or throat tightness
- Itching or skin rash
- Bumps on the skin called hives that can be red, pink, white, or brown depending on your skin tone
- Nausea or vomiting
- Dizziness, feeling lightheaded, or fainting
- Stomach cramps
- Joint pain
Precautions
Who should not use horny goat weed?
Allergies to Ingredients. People who are allergic to any of the following should not take horny goat weed.
- Barrenwort
- Bishop’s hat
- Epimedium species
- Herba epimedii
- Horny goat weed
- Yin yang huo (yinyanghuo)
- Any of the ingredients in the specific product
Your pharmacist can tell you all of the ingredients in the specific horny goat weed products they stock.
What should I know about horny goat weed before using it?
Horny goat weed is a dietary supplement. It cannot be marketed to treat or cure a disease.
Read and follow the directions on the specific product you are taking, or take it as recommended by your health care provider.
Keep horny goat weed out of the reach of children.
Horny goat weed may cause vertigo. Do not drive or do other activities that require alertness or coordination until you know how horny goat weed affects you.
Herbal products, such as horny goat weed, naturally contain many different chemicals. The amount of each chemical in a specific horny goat weed product can change for many reasons, including the area where the plant was grown, the weather during growth, the time of year when it was harvested, and the way that the plant was processed after it was harvested. If you switch to a new bottle or a different brand, you may not have the same effects or side effects because of this variability. Talk to your health care provider if you have questions or concerns.
Horny goat weed is available in many different forms, including as a tea, a liquid extract, and a dried ground powder found in tablets or capsules. Each of these forms may contain different amounts of the chemicals that are naturally found in the plant.
Many dietary supplements that are marketed for sexual performance have been found to contain prescription medicines or harmful chemicals. Some horny goat weed products have been found to contain prescription medicines that are not listed on the label. These prescription medicines can cause serious side effects and can also interact with other medicines. Use caution when buying a horny goat weed product because it may contain harmful ingredients that are not listed on the label. Find a list of potentially harmful products from the FDA here.
The FDA has not tested horny goat weed products to confirm that they contain the ingredients stated on their labels. Some dietary supplements have been tested by third-party organizations to confirm that they contain the ingredients listed on their labels and do not contain any harmful chemicals. Learn more about how to choose a safe dietary supplement product here.
What should I tell my health care provider before using horny goat weed?
Tell your health care provider about all of your health conditions and any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. This will help them know if horny goat weed is right for you.
In particular, make sure that you discuss any of the following.
Current and Past Health Conditions.Tell your health care provider if you have any of the following.
- Heart problems
- Hormone-sensitive cancer, such as breast or ovarian cancer
- Menopause
- Prostate problems
Other Medicines and Supplements.Horny goat weed may interact with other medicines and supplements. Before taking horny goat weed, tell your health care provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. See the Interactions section for more details.
Pregnancy. It is not known if or how horny goat weed could affect pregnancy or harm an unborn baby. Tell your health care provider if you are pregnant or plan to become pregnant.
Breastfeeding. It is not known if horny goat weed passes into breast milk. Tell your health care provider if you are breastfeeding or plan to breastfeed.
Interactions
Does horny goat weed interact with foods or drinks?
There are no known interactions between horny goat weed and foods or drinks.
It is unknown if drinking alcohol will affect horny goat weed, but drinking alcohol while taking horny goat weed may increase your risk for vertigo.
Does horny goat weed interact with medicines (drug interactions)?
Always tell your health care provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using.
In particular, make sure that you discuss if you are using any of the following before taking horny goat weed.
- A nitrate, such as nitroglycerin (Nitro-Dur, Nitrostat, and others) or isosorbide, which is a medicine used for chest pain caused by a type of heart disease, or a street drug, such as amyl nitrite (“poppers”)
- Hormone therapy or any other medicines that contain hormones, such as birth control
- Any medicine used for erectile dysfunction or pulmonary arterial hypertension
The interactions between horny goat weed and medicines are not fully understood. As with most dietary supplements, the research on drug interactions with horny goat weed is incomplete. Always check with your health care provider before taking horny goat weed with any medicines.
Dosing
What should I do if I accidentally use too much horny goat weed?
If you or someone else has used too much horny goat weed, get medical help right away, call 911, or contact a Poison Control center at 800-222-1222.
Horny goat weed comes in a range of doses and forms. But some horny goat weed products have been found to contain prescription medicines or harmful chemicals. Read the product label closely and speak with a health care provider about how to use horny goat weed safely. Do not take double or extra doses, even if you miss a dose.
References
- Gardner, Z; McGuffin, M. Botanical Safety Handbook (Second Edition), American Herbal Products Association, 2013.
- Khan, I; Abourashed, E. Leung’s Encyclopedia of Common Natural Ingredients (Third Edition), Wiley, 2010.
- LiverTox: Clinical and Research Information on Drug-Induced Liver Injury [Internet]: “Horny Goat Weed.”
- Memorial Sloan Kettering: “Epimedium.”
- Operation Supplement Safety: “Horny Goat Weed in Dietary Supplements.”
- US Food and Drug Administration: “EnShiShiXiangNiShangMaoYouXianGongSi Issues Voluntary Nationwide Recall of ENDURANCE BOOST WITH HORNY GOAT WEED Capsules Due To Presence of Undeclared Propoxyphenylsildenafil and Sildenafil.”