L-Arginine Side Effects, Risks, and Interactions

Consult your doctor if you have any concerns and be mindful of these side effects!

Most people taking L-arginine have little to no side effects. Using L-arginine—both orally and topically—is generally considered safe.

Consuming L-arginine from natural food sources isn’t harmful. However, unnaturally high doses from supplements may cause problems.

Possible side effects of L-arginine include:

  • nausea
  • dizziness
  • lightheadedness
  • weakness
  • cramps
  • abdominal pain
  • bloating
  • gout
  • diarrhea
  • allergic reactions
  • asthma symptoms
  • worsened allergies or asthma
  • airway inflammation
  • low blood pressure
  • changes to glucose and blood chemical levels
  • recurrence of symptoms associated with herpes simplex virus

Risks of L-Arginine

There are risks for taking L-arginine supplements if you have any of these medical conditions:

  • cancer
  • asthma
  • allergies
  • liver problems
  • kidney problems
  • low blood pressure
  • sickle cell disease,
  • bleeding disorders
  • heart problems
  • recent heart attacks (taking L-arginine after a heart attack may kill you)
  • herpes (L-arginine may make herpes worse. There is some evidence that suggests that the herpes virus needs L-arginine to multiply.)
  • recent surgery (L-arginine may interfere with blood pressure control both during and after surgery. Stop taking L-arginine at least 2 weeks before surgery.)

If you have or have had any of those medical conditions then do not take L-arginine without talking to your doctor first!

L-Arginine Interactions

L-arginine may interact and interfere with medicines or supplements. Talk to your doctor before taking L-arginine if you’re taking medication or supplements regularly.

Potential medication interactions wiith L-arginine include:

  • birth control medicines
  • hormone therapy drugs
  • blood thinners
  • anticoagulants
  • anti-platelet drugs
  • painkillers
  • erectile dysfunction medicines
  • heartburn medicines
  • high blood pressure medicines such as captopril, enalapril, losartan, valsartan, diltiazem, amlodipine, hydrochlorothiazide, and furosemide
  • diabetes medicines (L-arginine may decrease blood sugar levels in people with diabetes)
  • Isoproterenol (L-arginine might cause your blood pressure to become too low if you’re taking Isoproterenol)
  • Nitrates (L-arginine might cause your blood pressure to become too low if you’re taking Nitrates)

Potential supplement interactions with L-arginine include:

  • ginkgo biloba
  • garlic
  • Asian ginseng
  • potassium

Do not take these drugs with L-arginine:

  • amiloride (Midamor)
  • spironolactone (Aldactone)
  • triamterene (Dyrenium)

These drugs may interact with L-arginine to increase potassium levels. This increases the risk of developing hyperkalemia.

Do not take Sildenafil (Viagra) with L-arginine either because it may make your blood pressure drop too low.

L-Arginine for Children, Pregnant Women, & Breastfeeding Women

L-arginine should not be taken by children, by women who are pregnant, or by women who are breastfeeding without a doctor’s approval.

Some people suggest that L-arginine may be be safe in children and pregnant women. However, there isn’t much research on children and pregnant women so I wouldn’t use it in those scenarios (just to be on the safe side).

Sometimes, L-arginine is used to treat premature babies. Some children have died from high doses of L-arginine. Definitely talk to a doctor first.

People with Guanidinoacetate Methyltransferase Deficiency

People with Guanidinoacetate methyltransferase deficiency cannot convert arginine into creatine. This could cause problems.