People taking the following medications should avoid beta-carotene supplements:

Cholestyramine, Colestipol

Cholestyramine, a medication used to lower cholesterol, can lower blood concentrations of dietary beta carotene by 30 - 40 %, according to a 3-year study in Sweden. Colestipol, a cholesterol-lowering medication similar to cholestyramin, may also reduce beta-carotene levels.

Orlistat

You should not take beta-carotene with orlistat, a weight loss medication, because orlistat can reduce the absorption of beta-carotene by as much as 30 %, thereby reducing the amount of this nutrient in the body. If you must take both orlistat and beta-carotene supplements, you should separate the time between taking the medication and the supplements by at least 2 hours.

Other

In addition to these medications, mineral oil (used to treat constipation) may lower blood concentrations of beta-carotene and ongoing use of alcohol may interact with beta-carotene, increasing the likelihood of liver damage.