It follows a complaint from a health professional who found two blister strips of 10mg tablets inside a sealed box labelled 2.5mg.
The capsules were made at the same site, the MHRA said, and the error appears to have happened during the packaging process.
Dr Alison Cave, chief safety officer at the MHRA, said: “If you take Crescent Pharma Limited ramipril 2.5mg capsules, check the packaging for batch number GR155023.
“The batch number and expiry date information can be found on the outer carton. If you have received this batch, check that the medication strength on the carton matches the blister strips inside.
“If the 2.5mg carton of Crescent Pharma Limited ramipril contains blister strips that are labelled as ramipril 10mg capsules, do not to take the medicine and contact your dispensing pharmacy.
“If the carton contains blister strips that are correctly labelled as Crescent Pharma Limited ramipril 2.5mg capsules, you do not need to take further action and should continue to take your medicine as usual.
“If you have an affected pack or previously received this batch and you believe you have taken any ramipril 10mg capsules that were included in error and are currently experiencing any side effects, please seek medical advice.
“Signs and symptoms may include feeling light-headed, fainting or being fatigued, or altered kidney function, and may be more serious for vulnerable patients.
“Any possible impact of taking a higher dose of ramipril should be assessed by a healthcare professional to determine whether any examination or tests are needed.
“If you have this batch of medicine, please take the leaflet that came with your medicine and any remaining tablets with you to your pharmacy or GP practice. Any suspected side effects should also be reported via the MHRA Yellow Card scheme.”
The MHRA has also advised pharmacies and healthcare professionals to stop supplying the impacted batch and return all remaining stock to their suppliers.