Can vyvanse (lisdexamfetamine) cause false negatives on pregnancy tests?

Not likely.: This is not a known problem with vyvanse (lisdexamfetamine). But regardless of what meds you or are not taking, it's a good idea to repeat any lab test (particularly tests done at home)that you suspect as inaccurate. Also, if you are trying to get pregnant or not effectively blocking conception, i suggest you stop the vyvanse (lisdexamfetamine), along with almost all other medications that have not been specifically "ok'd" by your ob.