To reduce Chloroquine's (CQ) side effects, so that increasing its duration for anti-Covid-19 trials could be safe, the drug was potentiated by stabilizing it with Medicinal synthetic Aluminum-magnesium silicate (MSAMS). CQ-treatment for five Plasmodium berghie-infected mice-groups were: 7 mg/kg (normal dose); 7 mg/kg (CQ-MSAMS); 7 mg/kg (CQ-MSAMS + B-vitamins), 5.25 mg/kg (CQ-MSAMS + B-vitamins) and the control. Means of parasitaemia, 42.00 ± 15.74 of the normal-dose group, 37.22 ± 11.88 of the 7 mg/kg (CQ-MSAMS) group and 33.57 ± 12.62 of the 7 mg/kg (CQ-MSAMS + B-vitamins) group showed no significant (P ≥ 0.05) reduction from 52.50 ± 11.99 of the control, but the 5.25 mg/kg (CQ-MSAMS + B-vitamins) dose, cleared (P ≤ 0.01) the parasiteamia (00.00 ± 00.00), showing that MSAMS-potentiated Chloroquine, has best efficacy at 75% of the recommended dose. Fever and anemia were absent at that 5.25 mg/kg, suggesting that lower doses of CQ have reduced side effects.