Lansoprazole delayed-release capsules 15 mg / acid reducer. May take 1 to 4 days for full effect although some people get complete relief of symptoms within 24 hours. Clinically Proven To Treat Frequent Heartburn. Two-14-Day Courses of Treatment. Sodium Free. Treats frequent heartburn (occurs 2 or more days a week). Not intended for immediate relief of heartburn; this drug may take 1 to 4 days for full effect.