1 interaction was found for the drugs you selected.
CHOLESTYRAMINE in Cholestyramine Powder for Suspension
may interact with LEVOTHYROXINE in Synthroid
When these drugs are used at the same time, cholestyramine may combine with levothyroxine in the stomach and prevent it from being absorbed into the body. If this happens, then potentially less levothyroxine would be available for the body to use and blood levels could become too low. This could make levothyroxine less effective in correcting hypothyroidism (also referred to as an "underactive thyroid"). If these drugs are used together, allow at least 6 hours to pass after taking a dose of levothyroxine before using cholestyramine. Discuss this potential interaction with your healthcare provider at your next appointment, or sooner if you think you are having problems.
This interaction is poorly documented and is considered moderate in severity.