Is l-lysine safe to take during pregnancy?

Probably- moderation: As is usually the case, no research has been done so no one knows for sure. However, lysine occurs naturally in many foods so every woman who has ever been pregnant has consumed lysine in their diet. Thus, it is certainly safe in moderation. The only possible concern is high doses may lower levels of arginine, another amino acid. Doses up to 1500 mg/day are probably safe.