Horney goat weed is an herb traditionally used in Chinese medicine and alternative medicine circles to correct erectile dysfunction in men and to promote increased libido and sex drive in both men and women. Also called epimedium and yin yang huo, horney goat weed is typically available in tablet or capsule form at brick-and-mortar natural health centers, as well as online herbal stores. Evidence regarding side effects of horney goat weed is limited but points to certain--usually mild--problems that generally arise as a result of overdose or prolonged use of epimedium.
According to the Mayo Clinic, high doses of horney goat weed may result in breathing trouble when taken to correct erectile dysfunction problems. If you experience shortness of breath or begin to hyperventilate while taking horney goat weed supplements, discontinue your use of this herb until you consult with your doctor to determine the cause of your symptoms.
James Duke, Ph.D., retired U.S. Department of Agriculture botanist and author of "Handbook of Medicinal Herbs," cautions that extremely high intake of horney goat weed may lead to respiratory arrest or hyperreflexia, a condition characterized by overactive reflexes. Respiratory arrest is a potentially life-threatening medical emergency that requires immediate medical attention; if you experience this rare but serious condition while taking horney goat weed, stop taking the herbal supplement immediately.
Dizziness and Vomiting
If you experience unusual dizziness or vomiting after starting supplementation with horney goat weed, you may be suffering from other, less severe side effects of the herb, according to Dr. Duke. Mild nausea may occur as your body adapts to the horney goat weed, but if dizziness occurs on a regular basis or becomes severe, you may want to stop taking the supplement. Similarly, repeated vomiting typically indicates that you should stop taking the supplement.
Thirst and Dry Mouth
Excessive thirst and dry mouth may occur occasionally with horney goat weed intake, but they are generally not viewed as life-threatening side effects. Called xerostomia, dry mouth may lead to problems with tooth decay, since the decreased levels of mouth saliva fail to limit as much bacterial growth on your teeth, according to the Mayo Clinic. Monitor your daily intake of epimedium carefully, staying within commonly recommended daily dosages of two to four 500-milligram tablets. Talk to your doctor about adjusting your dosage, or you may want to stop taking the supplement completely if excessive thirst or dry mouth becomes problematic for you.