If the person you care for goes into hospital and their stay is arranged by the NHS, payment of their qualifying benefit will stop after 4 weeks (or 12 weeks in the case of a child with a disability who's under 16). As your Carer's Allowance entitlement depends on the person receiving a qualifying benefit, this will also stop at the same time.
Their benefits and your Carer's Allowance entitlement will also stop after 28 days if the person goes into a care home and their fees are paid in full by NHS continuing healthcare funding, or in full or part by the local authority.
If the person you care for is terminally ill and DWP knows this, their qualifying benefit may continue if they go into a non-NHS hospice. So you'll still receive your Carer's Allowance as long as you still provide care for 35 hours a week.
If the person you care for has regular periods of respite care, it might be possible to plan these periods so their qualifying benefit and your entitlement won't be affected. Seek advice if this applies.