Immunomodulators and immunosuppressants are the “big guns” of canker sore treatment. These are very powerful topical and oral medications that directly affect the immune system. They are more powerful than corticosteroids and are only used in severe cases of canker sores. Instances in which these powerful canker sore treatments would be used include patients that have recurrent major aphthous ulcers and in patients that have Human Immunodeficiency Virus (HIV) / Acquired Immune Deficiency Syndrome (AIDS) or Behçet syndrome.
Immunosuppressants and Immunomodulators
It is perhaps easiest to start with a description of immunosuppressants because their function is straightforward: they suppress the immune system. Immunosuppressants are probably best known for their use in autoimmune diseases and as drugs that prevent the immune system from rejecting transplanted organs. However, immunosuppressants also have a place in the treatment of canker sores. While it is unclear why canker sores happen, the way in which they cause scars is understood. The immune system destroys the mucosal cells of the mouth (mucosal cells cover most of the area you can see in your mouth). Therefore blocking the immune system can reduce or prevent tissue damage and scarring.
Immunomodulators are slightly different from immunosuppressants in that they alter the immune system in some way (not necessarily suppress it). In fact, some immunomodulators may actually increase the effects of the immune system, though in a way that is favorable for the patient. In terms of canker sore treatment, there is little difference between immunomodulators and immunosuppressants.
Azathioprine
Azathioprine is a powerful medication that interferes with the synthesis (formation) of DNA and RNA. Since the cells of the immune system multiply rapidly, this canker sore treatment blocks new immune cells from being created. Azathioprine is usually given orally as a medicine for canker sores but may be given intravenously (IV) in some cases. This medication cannot be given during pregnancy or if the patient has an active infection. Blood tests need to be performed periodically to check for side effects.
Thalidomide
If people have heard of thalidomide, they have no doubt heard about the horrible birth defects that occurred when this drug was first prescribed several decades ago. After much testing and trepidation, thalidomide is now back on the market in very select patients for very select diseases. Thalidomide is the only canker sore treatment specifically approved by the FDA for the treatment of recurrent aphthous ulcers in people with HIV. The drug seems to inhibit immune system cells from coming together and causing inflammation.
Clofazimine
Clofazimine is a drug that is used to treat leprosy but has been shown to be helpful in some cases of canker sores. The way in which clofazimine works is not exactly known but it seems to suppress the immune system and reduce inflammation.
Amlexanox
Amlexanox is a paste that is placed directly on aphthous ulcers. While it is not clear how this topical drug works, it appears to inhibit the release of chemicals that stoke up inflammation. By limiting these chemicals around the lesion, inflammation is reduced locally. Limited clinical studies show that this canker sore treatment may actually speed up canker sore healing.
Colchicine
Colchicine is best known as a treatment for gout in which it suppresses the immune system’s response to uric acid in the joints. For reasons that are not entirely clear, colchicine also works as a medicine for canker sores. The main side effect of colchicine is diarrhea, which limits its use as a canker sore treatment.
Miscellaneous immune system modifiers
Other agents have been tried in difficult cases with limited success. Other drugs that may be used to treat refractory (difficult to treat) aphthous ulcers are
- Adalimumab
- Alefacept
- Cyclophosphamide
- Cyclosporine
- Dapsone
- Efalizumab
- Etanercept
- Infliximab
- Interferon
- Methotrexate
- Penoxifylline
