Phenytoin and gum swelling
Why phenytoin is the textbook cause of gum overgrowth, who is most affected, and how to manage it without stopping seizure treatment.
Never start, stop, or change a medication based on what you read here. Bring questions to your dentist, physician, pharmacist, or prescribing clinician.
Quick answer
Phenytoin (Dilantin) is the original textbook cause of medication-induced gum overgrowth. The effect was first described in the 1930s and remains one of the most predictable drug-related dental side effects. Studies estimate visible overgrowth in roughly 50 percent of patients on long-term phenytoin, with higher rates in younger patients and those with poor plaque control. The management is similar to other gum overgrowth drugs: aggressive home hygiene, frequent professional cleanings, sometimes surgical reshaping. Switching to a newer anticonvulsant is sometimes possible.
The mechanism
Why phenytoin causes such consistent overgrowth
Phenytoin alters how gum tissue fibroblasts respond to stimulation. These cells, which normally build and remodel the connective tissue under the gums, become hyperactive and overproduce collagen. The presence of plaque amplifies the response: areas of plaque accumulation become areas of visible tissue overgrowth.
The pattern is recognizable. Phenytoin overgrowth tends to start at the papilla (the gum tissue between teeth) and spread, eventually covering meaningful portions of the tooth surface if untreated. The tissue is often firm rather than red and inflamed, which distinguishes it from ordinary gum disease. It rarely bleeds spontaneously but bleeds with brushing and flossing.
Risk factors include younger age (children and adolescents are particularly susceptible), poor plaque control, and higher doses. Newer anticonvulsants like levetiracetam (Keppra) and lamotrigine (Lamictal) have largely replaced phenytoin for new prescriptions, partly because they do not cause this overgrowth. Patients on long-term phenytoin who switch sometimes see substantial reduction in their gum tissue over months.
Practical steps
What to do about phenytoin gum overgrowth
Signs to watch for
When to call your dentist
- Gums that look puffy or are covering more of the teeth than before.
- Gums that bleed with brushing or flossing.
- Food getting stuck in places it did not before.
- Difficulty cleaning between teeth because of overgrown tissue.
- Cosmetic concerns about the gum line, especially in younger patients.
Common questions
What patients ask about Phenytoin and gum swelling and overgrowth
KYT Framework
KYT Framework connection
Four questions that shape how Phenytoin and gum swelling and overgrowth factor into dental planning.
Structure
Does gum swelling and overgrowth change bone, gum tissue, saliva, enamel, or healing support?
Force
Will chewing, grinding, or bite pressure create added risk for vulnerable teeth or healing tissue?
Timing
Is gum swelling and overgrowth something to prevent now, monitor, or evaluate soon?
Stability
What plan gives the mouth the best chance to stay stable?
Next steps
What to do about gum swelling and overgrowth
The medication side is usually not the right thing to change. The dental side is. Here is where to go next.
Taking Phenytoin and noticing gum swelling and overgrowth changes?
Bring your medication list. KYT can evaluate cavity risk, gum health, and treatment timing in person.
Reviewed by Dr. Isaac Sun, DDS · KYT Dental Services · Fountain Valley, CA · Last reviewed: June 2026
This page is general patient education. It does not replace advice from your prescribing clinician, physician, pharmacist, or dentist. Medication information may change; verify with your clinical team.