Probiotics, particularly Lactobacillus reuteri, have some of the strongest research for colic, with overall research quality ranging from low to high.[1][2][3][4][5][6][7][8][9][10] Generally, these studies gave probiotics to the mother during pregnancy and to the infant after birth.[1] No serious adverse events were reported.[1][11]
Fennel may be effective. In one study, fennel reduced total crying time by 72 minutes per day on average.[9] In another study, 65% of the participants taking 0.1% fennel seed oil resolved their colic, compared to 24% in the control group.[12] Evidence was rated as moderate quality.[13]
Sucrose was found in one study to reduce infant crying time by 101 minutes per day on average.[14] However, the evidence for this has been rated as very low quality.[13]
A trial combining fennel, chamomile, lemon balm, vitamin b1, vitamin b5, and vitamin b6 reduced crying time in infants with colic in the supplement group by 124 minutes, versus a reduction of 29 minutes in the placebo group.[15] The evidence for this was also rated as very low quality.[16]
No serious adverse events were reported for these supplements in colic.[13]