L-arginine Side Effects and Safety

L-arginine is a chemical building block called “an amino acid” that is used as a supplement to improve exercise function, boost sexual drive and performance, support the immune system and enhance the overall health.

Some people choose to supplement with L-arginine because L-arginine converts to nitric oxide, a vasodilator and blood vessel relaxant, which can improve cardiovascular conditions and erectile dysfunction.

L-arginine is a naturally occurring compound that our bodies can produce on their own. Thus, it is generally considered safe for the majority of users but may cause adverse effects in some cases.

It has not been clinically determined yet, how much L-arginine supplementation the average person can handle, making it possible to experience side effects when you supplement too much.

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L-arginine side effects can largely be prevented by avoiding high doses of this supplement and not combining it with other supplement or drugs that may result in a negative interaction.

Special Precautions and Warnings:

Pregnancy and Breastfeeding

L-arginine is possibly safe when ingested orally for a short-term during pregnancy. Not much is known about using L-arginine long-term during pregnancy or during breastfeeding. But it is recommended that you stay on the safe side and avoid use.


L-arginine is safe when used by mouth in premature infants in appropriate doses. However, L-arginine is possibly unsafe when used in high doses, since doses that are too high can cause serious side effects including death in children.

Digestive Problems

Excess intake of L-arginine can increase levels of stomach acid, particularly gastrin. Too much gastrin, on the other hand, can result in stomach pain and nausea, and you may also experience bloating, cramps and diarrhea.

Cirrhosis and Herpes

L-arginine should be used with caution in people with cirrhosis, and there is a concern that L-arginine might make herpes outbreak worse. It is believed that L-arginine is needed for the herpes virus to multiply.

Guanidinoacetate Methyltransferase Deficiency

People with this hereditary condition are unable to convert arginine and other similar chemicals into creatine. Thus, in order to prevent complications associated with this condition, these set of people should avoid taking arginine.

Allergic Reactions

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

Blood Pressure

Because of L-arginine’s properties as a vasodilator, low blood pressure can be a side effect of supplementing with this drug.

If you experience low blood pressure, you may feel dizzy, or blurred vision.

Recent Heart Attack

There is a concern that L-arginine might increase one’s risk of death after a heart attack, especially in older people. If you have suffered a heart attack recently, avoid taking L-arginine.

Chemical Imbalance

Because L-arginine is an amino acid, it can affect chemical and electrolyte levels. It can increase the body’s production of potassium, blood urea nitrogen, chloride, and creatinine. Sodium and phosphate levels may dive (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 their doctor first.


Since L-arginine might affect blood pressure, there is a concern that it might interfere with blood pressure control during and after surgery. So, stop taking L-arginine at least 2 weeks before a scheduled surgery.


Medications for high blood pressure interacts with L-ARGININE. L-arginine seems to decrease blood pressure, and taking L-arginine along with medications for high blood pressure might cause blood pressure to go too low.

Medications that increase blood flow to the heart (Nitrates) interacts with L-Arginine, which increases blood flow too. Thus, taking L-arginine with medications that increase blood flow to the heart might increase the chance of dizziness and lightheadedness.

Sildenafil (Viagra) can lower blood pressure, and L-arginine can also lower blood pressure. Taking sildenafil and L-arginine together might cause the blood pressure to go too low, and that has consequences. 


L-arginine is present in certain foods, so if you are going to supplement, take your diet into consideration when you consider a safe dosage.

Many nuts and seeds are high in this amino acid, as well as coconut, chocolate, corn, brown rice and some meats products.

If your diet is high in any of these foods, it is recommended that you begin supplementation at a low dose to monitor your body’s reaction.

An average dose of L-arginine is 2 to 3 g taken orally three times a day.

So, start on the low side of this recommendation, and if your body tolerates the supplements, you can gradually increase your dose.

You should also consult your doctor before you start taking any supplement to rule out any medical conditions that might be aggravated by the supplement.

Grant Philips

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