Saltwater Solution and Sodium Bicarbonate/Baking Soda - Mix 1 teaspoon salt with one cup warm water. Swish the solution in your mouth for 30 seconds, then expectorate (spit) the solution out of your mouth. In addition to salt, 1/2 teaspoon baking soda (sodium bicarbonate) may be added to the saline solution as well. Create a paste by mixing baking soda with small drops of water until a thick consistency has resulted. Use this paste to cover the canker sores, which will help relieve pain. These methods may be repeated as often as needed. Saline and sodium bicarbonate both help the mouth heal quickly by gently reducing the alkalinity and bacteria in the mouth.
Hydrogen Peroxide Solution - Mix one part hydrogen peroxide with one part water. Use a cotton swab to dab the solution directly onto the canker sores. Do not swallow the solution. Hydrogen peroxide is an antiseptic that will help reduce the amount of bacteria in the mouth.
Milk of Magnesia - Used frequently as an aide to relieve constipation and as an antacid, milk of magnesia is a liquid suspension of magnesium hydroxide. Dab milk of magnesia directly onto the canker sores with a cotton swab, three to four times a day. This method is recommended after using the hydrogen peroxide solution. Milk of magnesia will help reduce the pain and help speed the healing process.
Liquid Antihistamine - Diphenhydramine (Benadryl) may be used as an oral rinse by mixing one part milk of magnesia and one part diphenhydramine together. Rinse with the solution for one minute, then fully spit out the solution. Take care to avoid swallowing this mixture.
Over-The-Counter Oral Care Products and Mouth Rinse - Available in most dental care sections, antiseptic mouth rinses contain ingredients intended to help heal mouth sores by reducing the amount of bacteria in the mouth. Oral care products that are manufactured to numb painful areas in the mouth are also useful when treating canker sores. Products such as gels, paste, and rinses that are specifically marketed for mouth sores may provide pain relief and help speed the healing process. It is important that you follow the manufacturers' instructions closely when using over-the-counter products.
Oral Medications - Prescription medication may be necessary for treating serious canker sores that have developed into secondary infections. Tetracycline suspension (liquid) may be prescribed with instruction to hold the medicine in the mouth for two to five minutes before swallowing. Tetracycline is typically not prescribed for children as it has been shown to cause permanent discoloration in developing teeth. Zovirax (Acyclovir) is an antiviral drug that may be prescribed for cases where there are multiple, very painful canker sores.