A cavity means presence of bacteria. These bacteria will demineralise your tooth by releasing acids. These acids will eat away the tooth structure resulting in tooth decay. Since you said it has spread to other tooth, it means the decay is active and progressive. It will not be stopped completely by medicines or any other
aids. You may delay the process but you cannot stop it completely without the intervention of the Dentist.
Next Steps
Visit your dentist immediately.
Health Tips
If neglected, decay will progress and may cause pain which should be treated by root canal treatment.