Icariin side effects may be experienced by those supplementing with the horny goat weed.
Icariin is considered the active ingredient in horny goat weed, a supplement extracted from plants of the Epimedium genus.
Icariin concentrations will vary between horny goat weed supplements, but high quality brands will list the concentration of icariin, which can reach up to 60 percent.
Horny goat weed has been used for centuries in traditional medicine systems throughout Asia. It is particularly common in traditional Chinese medicine where the supplement is known by its Chinese name, yin yang huo.
Horny goat weed is generally well tolerated and side effects are rare when the supplement is taken appropriately and for short periods of time. Adverse Icariin side effects are often caused by taking high doses or by combining this supplement with drugs or herbs that may cause an interaction.



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Icariin Overview
Related Topics
Epimedium has been used as a medicinal agent throughout Asia, including Korea, Japan and China, for more than a thousand years.
Horny goat weed is now distributed worldwide and remains one of the most popular herbal agents available.
It is primarily used for sexual dysfunction, erectile dysfunction, low libido, fatigue and athletic performance. Icariin is the active phytochemical (plant chemical) in Epimedium and is believed to be responsible for horny goat weed’s purported medicinal properties.
To date, icariin has demonstrated antioxidant, anti-inflammatory, cardioprotective, renoprotective and hepatoprotective properties in laboratory experiments. Research continues to investigate its therapeutic uses.
Icariin Side Effects and Safety
Horny Goat Weed is rated as Possibly Safe by the Natural Medicines database when it is taken orally and appropriately. However, it is rated Possibly Unsafe if it is used at high dosages for long periods of time.
According to Natural Medicines, icariin has been used safely for up to six months in one clinical trial. This study used an aqueous extract or a tincture of horny goat weed standardized to contain 25.36% icariin. Another study used 60 mg of icariin combined with other herbs for up to two years.
In general, Epimedium supplementation is well tolerated, but may cause minor gastrointestinal distress. Prolonged and excessive supplementation can lead to a number of more serious side effects.
Reported Adverse Effects of Icariin
Excessive Epimedium supplementation may cause tachyarrhythmias (abnormal heart rhythms). This may be the result of overly dilated coronary vessels and/or excessively low blood pressure.
In animal tests, icariin side effects include decreased activity of the thyroid gland.
Excessive supplementation may cause nausea, vomiting, diarrhea and/or dryness of the mouth and/or throat. Hematologic icariin side effects may include nosebleeds.
In the musculoskeletal system, too much icariin may cause exaggerated tendon reflex stimulation and result in joint pains. Also, muscle spasms have been reported. Neurological side effects of excessive icariin consumption may include dizziness, increased aggression and/or irritability.
In the pulmonary/respiratory system, high doses of icariin may cause complete respiratory arrest. More commonly, breathing difficulties and shortness of breath have been reported.
Icariin Drug Interactions
Be sure to speak with your doctor before taking icariin or horny goat weed supplements, especially if you are taking prescription medications or have been diagnosed with any medical conditions. This supplement may also interact with certain herbs and nutrients.
Icariin possesses a number of medicinal traits that may cause it to interact with prescription, herbal and over-the-counter medications. For example, Epimedium may interact with anticoagulant/antiplatelet drugs and increase the effects of these medications, which can lead to increased risk of excessive bleeding.
It is important to note that these observations have not been made in any human cases. Nevertheless, in the absence of clinical data it is important to exercise caution if using icariin supplements along with aspirin, Plavix, Fragmin, Lovenox, Ticlid, Coumadin, heparin and other similar substances.
Icariin may interact with antihypertensive drugs. Epimedium has been observed to exhibit hypotensive effects and blood pressure may drop excessively when used in combination with antihypertensive agents. Be careful if using horny goat weed with drugs like Vasotec, Altace, Zestril, Prinivil, Capoten, lisinopril and other similar prescription drugs.
Side effects may occur when icariin is combined with estrogenic compounds. The likelihood and severity of such interactions are moderate, but should be carefully considered.
Horny goat weed supplementation has been observed to increase the amount of estrogen in the blood of some women. The adverse and therapeutic effects of estrogen agents may be heightened when used in combination with icariin.
Be cautious of mixing Epimedium supplements with prescription medications for prolonging QT intervals in cardiac patients. Horny goat weed supplementation may increase QT intervals and cause dangerous complications, including sudden cardiac arrest.
Speak with your cardiologist about combining Epimedium extract supplements with heart medications, including Cordarone, Norpace, Betapace, Mellaril, Pronestyl and various others.
Use caution when combining horny goat weed with other herbs, including, garlic, ginger, cloves, angelica, quassia, red clover, turmeric, danshen, willow and ginkgo biloba. Also exercise caution if stacking with stinging nettle, L-arginine, theanine, lycium, coenzyme Q10, cat’s claw, fish oil and/or casein peptides.
Epimedium is not known to interact with any particular foods.
Conclusion
While Icariin and Horny Goat Weed are considered Possibly Safe for short-term use, there can be negative side effects if it is used at high dosages for long periods of time. Be sure to speak with your doctor before beginning supplementation to make sure you understand all the possible side effects of icariin.
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Article last updated on: April 6th, 2018 by Nootriment