What are the causes of canker sore?

Canker sore. Canker sores can be caused by stress, trauma, Vitamin deficiency, hormonal, autoimmune, sensitivity to certain chemicals. A common sensitivity is to SLS, sodium lauryl sulfate, which is common in many toothpastes. Try one without SLS if you have frequent canker sores.
Be sure of diagnosis. Get examined please. Canker sores are common aphthous ulcers of mouth that occur situationally, often in response to stressors, are bacterial or viral, & can be treated topically with many otc products that reduce local discomfort &potentially speed healing. However, oral/dental problems &a number of systemic diseases cause canker sore-like lesions--crohn's, behcet's, STD to mention a few.
Canker sores. Stress, tissue injury, certain foods, impaired immune system; nutritional problems, such as vitamin b-12, may be viral as well if not really canker but cold sore.
Unknown. Any other answer is wishful fantasy.

Related Questions

What can cause getting a canker sore and how can I get rid of it?

Herpes Virus. Almost everyone has this virus. Periodocally it erupts. It starts as a small blister, ruptures, and ends up as a whitish ulcer with a red border. It goes away in about a week. If you are a 5+/- year old, and this is your first episode, it is a little different. These are usually on attached keratinized tissue. They still end up the same way. Later episodes are as described above. They are not. Read more...
Canker Sores. are the most common oral lesions. Individual ulcers typically last 1-2 weeks. The cause is not known. The ulcers are usually self-limiting. Try to keep adequate oral hygiene as possible. Read more...

Can having oral sex with someone who has a canker sore cause problems?

Protect yourself! Exposing yourself to a possible infectious agent from an open wound is never a good idea! if your partner's "canker sore" turns out to be a herpes lesion, you run the risk of getting a herpes (type 2) infection on your private parts. Such a herpes infection become potentially a lifelong relapsing & painful problem that you can then pass on to others--not a good tradeoff for an impulsive moment. Read more...
Yes. Depending on the type of sore, and whether or not you have already been exposed to the same virus in the past, you could pick up the infection. Once you do, it's yours for life. Read more...

My boyfriend told me that every time after he gives me oral sex he gets a canker sore, we have both been tested and are negative, what can be the cause?

Stress etc. Cold sores are a result of a virus that is already in his "system" and comes out as a result of stress. Canker sores may result from localized trauma/injury, lowered resistance, lack of sleep, etc. Read more...
Local trama. The activity of oral sex may provide enough trama to inner lip or cheeks that may trigger an outbreak of a canker sore or apthous ulcer. These are not infectious or caused by bacteria or virus, just body reaction to some trigger, like stress, trama, certain foods or food coloring or flavorings, etc. Read more...

How can I get rid of a canker sore what. Causes them?

Canker sores. Cause unknown (stress\local irritation)? Nature will heal the sore. Topical medications at pharmacy or supermarket may help it feel better meanwhile. I just ride it out myself. See: http://www.mayoclinic.org/diseases-conditions/canker-sore/basics/definition/con-20021262. Read more...
Manage Canker sores. Canker sores are viral. Manage symptomatically. See a DDS/DMD who treats this for oral medicines and anti- viral salves. This will help. Go online to www.health911.com and link to cold sores for homeopathic remedies. Dehydration and prolonged sun exposure encourages these out breaks. Read more...

Could vomiting a lot cause cold sore and canker sore?

No and yes. No to the cold sore as it is caused by a virus and yes to the canker sore which may be induced by local irritation. Read more...
Definitely, no. Canker sore 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. Cold sores typically result from a viral infection called herpes simplex virus (HSV). Vomiting is not a cause for cold sore or canker sore. Read more...