Get 24-hour relief from frequent heartburn with Nexium 24HR Capsules. Nexium 24HR Capsules work by blocking acid directly at the source, giving you 24 hours of protection from frequent heartburn. Just one Capsule a day provides all-day, all-night protectionfrom frequent heartburn. Use as directed for 14 days to treat frequent heartburn. Do not take for more than 14 days or more often than every 4 months unless directed by a doctor. Not for immediate relief. Nexium 24HR may take 1-4 days for full effect.