The Side Effects of Too Much L-Arginine

L-Arginine is an amino acid normally produced by the body in the amounts needed for proper functioning. Most people do not need any more L-arginine than what their bodies naturally supply. Some choose to supplement, however, because L-arginine converts to nitric oxide, a blood vessel relaxant, which can improve cardiovascular conditions and erectile dysfunction. L-arginine also prompts the body to produce protein, offering an advantage to bodybuilders. It hasn't been decisively determined yet, however, how much L-arginine supplementation the average person can handle. In some cases, it is possible to supplement too much and cause side effects to occur.

Doctor checking patients blood pressure. (Image: XiXinXing/XiXinXing/Getty Images)

Digestive Problems

L-arginine can increase levels of stomach acid, particularly gastrine. Too much gastrine can result in stomach pain and nausea. You may also experience bloating, cramps and diarrhea.

Allergic Reactions

Some people experience anaphylaxis, or an allergic reaction, to L-arginine. The severity of anaphylaxis increases with dosage. Symptoms include itches and skin rashes, swollen eyes, and in the worst cases, shortness of breath. People with asthma may be especially prone to this.

Blood Pressure

Because of L-arginine's properties as a vasodilator, low blood pressure can be a side effect of supplementation. If you experience low blood pressure, you may notice dizziness, fainting or blurred vision. Contact your doctor immediately if you experience these or other associated symptoms.

Chemical Imbalance

Because it is an amino acid, L-arginine can affect chemical and electrolyte levels. It can increase the body's production of potassium, chloride, creatinine and blood urea nitrogen. Sodium and phosphate levels may lower. Those suffering from kidney or liver problems are especially susceptible to changes in these chemical balances and should never supplement with L-arginine without talking to a physician first.


L-arginine is also present in certain foods, so if you're going to supplement, take your diet into consideration when you factor a safe dosage. Many nuts and seeds are high in this amino acid, as well as raisins, coconut, chocolate, corn, brown rice and some meats. If your diet is high in any of these things, begin supplementation at a low dose to gauge your body's reaction. A standard dose of L-arginine is 2 to 3 g taken orally three times a day. Start on the low side of this recommendation, and if you tolerate the supplements, you can gradually increase your dose. You should also confer with your doctor before you start taking any supplement to rule out any medical conditions that might be aggravated or worsened by L-arginine.

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