Mouth Sore Won't Go Away? A Dental Hygienist Explains Common Causes and Treatment
Written by by Jasmine RDH, BSDH, MHA | Registered Dental Hygienist with 13+ Years of Clinical Experience
If you have a mouth sore that will not heal, you're not alone.
One of the most common questions patients ask is: "Why do I keep getting mouth sores?" While most mouth sores are harmless and heal on their own, some can signal an underlying health issue that should not be ignored.
Here's what you need to know.
What Is a Mouth Sore?
A mouth sore is a painful area that develops on the tongue, cheeks, gums, lips, or roof of the mouth.
The most common type is a canker sore, also called an aphthous ulcer.
Most mouth sores appear as:
• Small white or yellow ulcers
• Red or inflamed borders
• Pain when eating, drinking, or brushing
Unlike cold sores, canker sores are not contagious.
What Causes Mouth Sores?
Several factors may contribute to mouth sores.
Common causes include:
• Stress
• Minor injuries from biting the cheek or tongue
• Aggressive brushing
• Braces or dental appliances
• Vitamin B12 deficiency
• Iron deficiency
• Hormonal changes
• Acidic foods
• Certain medications
• Immune system disorders
In many cases, mouth sores result from a combination of factors rather than a single cause.
How Long Do Mouth Sores Last?
Most mouth sores heal within 7 to 14 days.
Small sores often resolve within one week, while larger sores may take longer.
If a sore lasts longer than two weeks, it should be evaluated by a dental professional.
How Can You Make a Mouth Sore Heal Faster?
There is no instant cure for a mouth sore, but several strategies may help reduce irritation and support healing.
Try these steps:
• Rinse with warm salt water
• Stay hydrated
• Avoid spicy foods
• Avoid acidic foods
• Use a soft bristled toothbrush
• Maintain good oral hygiene
• Avoid touching or irritating the sore
Keeping the area clean can help prevent additional irritation.
What I Tell My Patients
As a Registered Dental Hygienist, one of the biggest mistakes I see is patients ignoring a sore that has not healed for several weeks.
Most mouth sores are harmless. However, any sore that persists beyond two weeks deserves professional evaluation.
Changes inside the mouth are often easier to treat when identified early.
If something feels unusual, trust your instincts and schedule an examination.
When Should You See a Dentist for a Mouth Sore?
Schedule an evaluation if:
• The sore lasts longer than two weeks
• You experience severe pain
• Eating or drinking becomes difficult
• The sore continues to grow
• You develop multiple sores repeatedly
• You notice swelling or fever
Persistent oral lesions should always be examined by a healthcare professional.
Frequently Asked Questions
Why do I keep getting mouth sores?
Recurring mouth sores may be linked to stress, nutritional deficiencies, irritation, hormonal changes, or certain medical conditions.
Are mouth sores contagious?
Most canker sores are not contagious. Cold sores, which are caused by a virus, can spread through direct contact.
Can toothpaste cause mouth sores?
Some people may experience irritation from certain toothpaste ingredients. If sores occur frequently, discuss your oral care products with your dental professional.
Should I brush my teeth if I have a mouth sore?
Yes. Continue brushing gently while avoiding direct irritation of the affected area.
When should I worry about a mouth sore?
Any sore lasting longer than two weeks should be professionally evaluated.
The Bottom Line
Most mouth sores heal on their own within one to two weeks. Maintaining good oral hygiene, avoiding irritation, and staying hydrated can help support healing.
If a mouth sore persists, recurs frequently, or causes significant discomfort, consult your dental professional for a proper evaluation.