Chronic use of Senna

[soregut]

I have IBS-c and have used Senna fruit tablets, 2 at night fairly constantly over 6 months.Some research papers say it shouldn't be used chronically as it can cause a lazy bowel but others say there is no good evidence that Senna fruit can damage the colon. Has anybody any experience of long term use of Senna? Even with it I still get periodic constipation needing rescue with Picolax.

Thanks.