L-arginine can cause some side effects, such as bloating, low blood pressure, airway inflammation, abdominal pain, allergies, gout, diarrhea and blood abnormalities, as stated by WebMD. However, L-arginine is generally safe if used on the skin, given as an injection or taken by mouth, as directed by a doctor.
This medication may also interact with other drugs, as stated by MedlinePlus. It is strictly advisable not to use L-arginine with medications for hypertension, as it will lead to decreasing of blood pressure. It may have moderate interactions with ACE inhibitors, diabetes medications, Viagra, nitrates, anticoagulant and angiotensin receptor blockers, among others. Therefore, it is necessary to inform the doctor of any current medications.
L-arginine is safe for pregnant women when taken by mouth for short-term use. There is not enough information for pregnant and breastfeeding women if used on a long-term basis. Refraining from using this medication may be a safer option, as stated by WebMD.
L-arginine is unsafe for children when taken excessively and can be potentially life-threatening. It can lead to allergies or make an existing airway condition worse. Patients suffering from low blood pressure, kidney disease, cirrhosis, herpes and those who had a recent heart attack are advised not to use L-arginine.