Rennie belongs to the group of medicines called combinations and complexes of aluminum, calcium and magnesium.
It contains as active substances calcium carbonate and magnesium carbonate, which act by neutralizing excess acid in the stomach Rennie is indicated for the relief and symptomatic treatment of heartburn and heartburn in adults and adolescents over 12 years of age.
You should see a doctor if it gets worse or doesn't improve after 7 days.