Why Do I Keep Getting Canker Sores?

It’s a tiny white spot on the inside of your lip, and it has the personality of a thumbtack. Orange juice is out. The toothbrush is a negotiation. You had one of these a few months ago, and you’re pretty sure it came back right around your period.

What sets them off

Cleveland Clinic³ says stress and minor injuries to the inside of the mouth are possible triggers. Other factors on its list are nutritional deficiencies (B12, D, folate, iron, zinc), immune system conditions, medicine side effects, acidic or spicy foods and toothpastes containing sodium lauryl sulfate.

Hormones. Cleveland Clinic³ says females are more susceptible than males, and that changing hormone levels during your period can trigger a sore. The National Institute of Dental and Craniofacial Research (NIDCR)⁴ says canker sores are most common in puberty, when certain growth-related hormones are higher, and lists hormonal imbalances among triggers.

Nutrients. The NIDCR⁴ lists nutritional deficiencies in folic acid, iron or vitamin B12. The NHS² names a vitamin deficiency such as iron, zinc, folic acid, vitamin B or vitamin D.

Injury. The NHS² lists biting the inside of your cheek, ill-fitting dental work and sharp foods. It also lists stress and hormonal changes such as during pregnancy.

How long they last

The ADA¹ says canker sores usually heal on their own after one or two weeks. Cleveland Clinic³ says the pain usually improves in a few days and that the ulcers typically heal within two weeks even without treatment, though major ones can take months.

What helps

The NHS² says there’s no quick fix, and that the sores need time to heal. It suggests a soft toothbrush, cool drinks through a straw and avoiding heavily spiced, salty or acidic foods. It describes a salt-water rinse of half a teaspoon of salt in warm water. A pharmacist can recommend antimicrobial mouthwash, painkillers or corticosteroid lozenges.

The ADA¹ says over-the-counter topical anesthetics and antimicrobial mouthwashes can give temporary relief, and to stay away from hot, spicy or acidic foods. It says a dentist can prescribe antibiotics and oral bandages to reduce secondary infection. The NIDCR⁴ says OTC numbing gels can ease pain and that rinsing with an OTC antiseptic may help prevent infection and speed healing.

Cleveland Clinic³ lists alcohol-free mouth rinses and notes that prescription options exist for severe cases.

The play

Try this: a flare diary and a toothpaste swap

For two or three months, write down when each sore appears, where, how long it lasts and what came before it: your cycle day, a stressful week, an injury, a new food, a new product.

Cleveland Clinic³ lists sodium lauryl sulfate in toothpaste as a possible trigger. Check your tube and try one without it if yours has it, then see if the flares change.

Bring the diary to your dentist or doctor if the sores keep coming.

When to get checked

Cleveland Clinic³ says to contact your provider if sores last beyond two weeks, are larger than a centimeter, come with flu-like symptoms, return several times a year or interfere with daily activities. The NIDCR⁴ says to see a doctor if you have frequently recurring canker sores or if they make eating or drinking difficult. It adds that people with recurring sores should talk with their doctor about testing for celiac disease or nutritional deficiencies.

The NHS² says to see a dentist or GP if a mouth ulcer lasts longer than 3 weeks, because a long-lasting mouth ulcer is sometimes a sign of mouth cancer.

Book an appointment if any of these fit:

• A sore has lasted more than 2 weeks, or has passed 3 weeks
• A sore is larger than a centimeter, or keeps getting bigger
• You have flu-like symptoms or a fever with it
• You get sores several times a year
• You can’t eat or drink comfortably
• You’d like to be tested for celiac disease or low nutrients, which the NIDCR⁴ says to discuss when sores recur

One sore around your period is a nuisance. Sores that keep returning are a pattern, and the diary is how you show it.