Safety and side effects

Using L-arginine orally or topically is generally considered safe.

Oral use of L-arginine might cause:

• Nausea, abdominal pain and diarrhea
• Bloating
• Gout
• Headache
• Allergic response
• Airway inflammation or worsening of asthma symptoms

L-arginine isn't recommended for people who have had a recent heart attack due to concerns that the supplement might increase the risk of death.

L-arginine can worsen allergies or asthma. Use the supplement with caution if you have these conditions.

Be careful about taking L-arginine if you've had cold sores or genital herpes. Too much L-arginine in your system can potentially trigger the virus that causes those conditions.