• Anticoagulants and anti-platelet drugs, herbs and supplements. These types of drugs, herbs and supplements reduce blood clotting. Taking L-arginine with them might increase the risk of bleeding.
• Blood pressure drugs, herbs and supplements. L-arginine might reduce blood pressure in people who have high blood pressure. Combining use of L-arginine with a blood pressure drug, herb or supplement might increase the risk of blood pressure becoming too low.
• Diabetes drugs, herbs and supplements. L-arginine might decrease blood sugar levels in people with diabetes. If you’re taking diabetes drugs, herbs or supplements, your dosage might need to be adjusted.
• Sildenafil (Viagra). Use of this erectile dysfunction medication with L-arginine might cause your blood pressure to become too low.
• Isoproterenol. Use of this heart medication with L-arginine might cause your blood pressure to become too low.
• Nitrates. Use of this chest pain medication with L-arginine might cause your blood pressure to become too low.
• Water pills (potassium-sparing diuretics). Don’t take amiloride (Midamor), spironolactone (Aldactone) or triamterene (Dyrenium) with L-arginine. These medications can increase potassium levels, increasing the risk of developing a higher than normal level of potassium in your blood (hyperkalemia).

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.

L-arginine isn’t recommended (directly) after a heart attack due to concerns that the supplement might increase the risk of death.

Source: https://www.mayoclinic.org/drugs-supplements-l-arginine/art-20364681