Aphthous ulcers (aphthae, recurrent aphthous stomatitis or canker sores). Aphthous ulcers occur at some time in 1 in 5 people, most commonly in teenagers and young adults.  They are areas of round or oval skin loss on the inner wet surfaces of the mouth or genitalia, such as inside the lips, cheeks or under the tongue.   Most aphthous ulcers are recurrent minor aphthous ulcer (recurrent aphthous stomatitis).  The cause is unknown but may include stress, injury to the skin, vitamin and mineral deficiency and vary with periods.  Sometimes they run in families.

They may rarely be associated with some illnesses that affect the immune response, including Behcet disease, HIV/AIDS, Coeliac disease and inflammatory bowel disease.
They may be more severe and a response to illness or infection (Lipschutz ulcer).

Patient information

• Patient.co.uk:  http://www.patient.co.uk/health/Mouth-Ulcers-%28Minor-Aphthous-Type%29.htm
• http://www.netdoctor.co.uk/mouthandteeth/ulcers.htm
• NHS Choices:  http://www.nhs.uk/conditions/mouth-ulcer/Pages/Introduction.aspx
• American Family Physician: http://www.aafp.org/afp/20000701/160ph.htm
• Dermnet NZ:   http://dermnetnz.org/site-age-specific/aphthae.html

Do I need any tests?
A biopsy of a genital ulcer may be done to confirm the diagnosis.
Blood tests may also be done to make sure you are not anaemic, or short of iron or vitamins.

Treatment
There is no cure for aphthous ulcers but most heal within 2 weeks.
The genital ulcers are helped by a hygiene regime that does not irritate as harsh washing and cleansing of the vulva can make it more dry, irritated, sore and itchy. If passing urine is very painful or difficult it can be helpful to urinate in a warm bath.
For advice on caring for the vulval area:
Care Down There http://www.caredownthere.com.au/_pages/information_care.html
International Society for the Study of Vulvovaginal Disease: Mike can you make sure this link is to the PDF the ISSVD supplied
British Association of Dermatologists: http://www.bad.org.uk/Portals/_Bad/Patient%20Information%20Leaflets%20(PILs)/Care%20of%20Vulval%20Skin%20Mar%202009.pdf

Specific treatments
Steroid applications (creams, ointments, foams, mouthwashes, sprays and pastes) and other applications can help with the symptoms. 
If very painful and recurrent, steroids tablets and other tablets are useful.
Treatment guidelines and information

Emedicine Aphthous Stomatitis:  http://emedicine.medscape.com/article/1075570-overview American Family Physician:  http://www.aafp.org/afp/20000701/149.html

Some approaches to treatment have been reviewed for the Cochrane Library:
Interventions for recurrent aphthous stomatitis (mouth ulcers)
http://onlinelibrary.wiley.com/doi/10.1002/14651858.CD005411