I have had this canker sore for a week?

Canker sore: Canker sores typically take 10-14 days to heal. You should be seeing signs of healing, such as decreasing size and sensitivity. If you have concerns then see a dentist for evaluation.

7-10 days is normal: Where is the canker sore located? Typically a week to 10 days is normal for these to resolve themselves but your dentist can apply a topical cauterizing agent that will speed up the resolution if you can't wait for it to heal. If you are prone to getting these a lot in your mouth you may want to try a new toothpaste that is SLS free (Sodium Lauryl Sulfate).

Canker sore : Canker sores are the most common oral lesions. Individual ulcers typically last 1-2 weeks. The condition is idiopathic (cause is not known) recurrent aphthous ulcers is usually self-limiting. Try to keep adequate oral hygiene as possible. If concerned see your dentist after 10 days or visit today for laser immediate amelioration.