Best calming supplements, ranked.

The canonical alpha-casozepine calming supplement, a milk-protein hydrolysate with modest but real randomized-trial support for situational stress in cats and dogs, NASC-sealed with a restrained non-sedating claim. It scores on a moderate evidence tier, not a strong one, and at over a dollar a day it runs expensive for the category.

The studied L-theanine form, fully disclosed and very cheap per day, but at 5 mg it is well under the studied dose; weak evidence and a low dose hold it to Mixed.

A calming chew scored on its disclosed L-theanine (the studied Suntheanine form); the C3 colostrum complex is not in our evidence library and at 21 mg the L-theanine is below the studied dose, so it lands Mixed.

The veterinary-strength Composure, scored like the regular version on its disclosed Suntheanine L-theanine, with added L-tryptophan and a higher thiamine load; at 25 mg the L-theanine is still below the studied dose and the C3 colostrum complex is not in our evidence library, so despite the clinical-onset marketing it lands Mixed, the same band as the standard Composure.

The one calming product with a dedicated canine anxiety RCT (B. longum BL999), at the studied dose and fully disclosed; no NASC seal and a high cost per day hold it to Mixed.

Transparent and inexpensive, but a weakly-evidenced calming active (L-tryptophan) delivered well below the studied dose for a 22 lb dog keeps it Mixed.

A fully disclosed calming chew from an NASC brand, scored on its L-tryptophan, which is the active in our evidence library; at 30 mg the tryptophan is well under studied calming doses and its evidence tier is the weakest in the calming category, so good label execution still lands it at the Mixed-to-Limited line rather than higher.