Three classes of drugs are responsible for the vast majority of gingival hyperplasia, also called drug-induced gingival overgrowth: anticonvulsants (especially phenytoin), calcium channel blockers (especially nifedipine), and the immunosuppressant cyclosporine. The condition typically appears within one to three months of starting the medication, beginning as painless swelling between the teeth before potentially growing into thick tissue folds that cover portions of the tooth crowns.
Anticonvulsants: Phenytoin and Others
Phenytoin is the most well-known cause of gingival overgrowth and was the first drug linked to this side effect. About 50% of people on long-term phenytoin therapy develop some degree of gum enlargement, though reported rates range widely from 3% to 93% depending on the population studied. Children taking phenytoin are more commonly affected than adults.
Phenytoin isn’t the only seizure medication involved. Carbamazepine, valproic acid, barbiturates, and succinimides have all been reported to cause gingival overgrowth, though far less frequently. If you’re taking an anticonvulsant and notice your gums changing, phenytoin is by far the most likely culprit, but other medications in this class can occasionally be responsible.
Calcium Channel Blockers: Nifedipine Leads the List
Calcium channel blockers are widely prescribed for high blood pressure and heart conditions, and several of them can trigger gum overgrowth. Nifedipine carries the highest risk, with reported prevalence rates between 20% and 83%. In one hospital-based study, 75% of patients taking nifedipine showed signs of gingival overgrowth.
Other calcium channel blockers carry lower but real risk. Diltiazem has been associated with overgrowth in up to 74% of patients in some reports, while verapamil sits around 21%. Amlodipine, one of the most commonly prescribed blood pressure medications, has the lowest reported rates in this class, generally between 1.7% and 3.3%. If you develop gum changes on nifedipine, switching to a different blood pressure medication is one of the first strategies your doctor may consider. In studies where patients were switched from nifedipine to a different calcium channel blocker (isradipine), the overgrowth regressed.
Cyclosporine
Cyclosporine is an immunosuppressant used most often after organ transplantation and for certain autoimmune conditions. Roughly 43% of transplant patients on cyclosporine develop gingival overgrowth. The link became apparent shortly after the drug was introduced for human use in 1978, and it remains one of the most predictable drug-related causes of the condition.
Because transplant patients often can’t simply stop cyclosporine, managing the overgrowth typically relies heavily on rigorous oral hygiene and, when needed, surgical removal of excess tissue.
What Happens Inside the Gums
Although these three drug classes work very differently in the body, they share a common effect on gum tissue. They interfere with how gingival cells process folic acid, which disrupts the normal breakdown of collagen. Healthy gums constantly remodel themselves, building up and breaking down connective tissue in balance. These drugs tip that balance by reducing the activity of enzymes that clear away old collagen. The result is a buildup of excess connective tissue that presents as visible gum enlargement.
The overgrowth typically starts as small, bead-like swellings of the gum tissue between the teeth. Over time, these swellings expand along the gumline and can merge into large tissue folds that partially or fully cover the teeth. The front teeth are most commonly affected.
Risk Factors That Make It Worse
Not everyone on these medications develops overgrowth, and among those who do, severity varies widely. Several factors influence your risk beyond the drug itself.
Plaque buildup is the single most important modifiable factor. Bacterial plaque triggers gum inflammation, and that inflammation appears to accelerate the overgrowth process. The relationship creates a frustrating cycle: swollen gums are harder to clean, which leads to more plaque, which leads to more inflammation and further swelling. Some researchers believe plaque is actually a prerequisite for the condition to develop at all, while others view it as a consequence of the enlargement that then makes everything worse. Either way, controlling plaque consistently reduces severity.
Genetic predisposition plays a significant role. Two people on the same dose of the same drug can have completely different outcomes based on their individual biology. Age and sex also matter. The condition is most commonly seen in male children and adolescents, and children are more frequently affected than adults overall. Higher drug dosages generally correlate with more severe overgrowth, though even low doses can cause problems in susceptible individuals.
How Gingival Overgrowth Is Managed
The most effective approach, when medically possible, is switching to a different medication that doesn’t cause gum changes. For blood pressure patients on nifedipine, alternatives like amlodipine (which has a much lower incidence) or non-calcium-channel-blocker medications may be options. For seizure patients on phenytoin, other anticonvulsants may work equally well without the gum side effect. These decisions depend on how well the underlying condition is controlled, so they require coordination with the prescribing doctor.
Regardless of whether the medication changes, aggressive plaque control is essential. Professional dental cleanings combined with thorough daily brushing and flossing can significantly reduce severity and, in some cases, prevent the overgrowth from progressing. This is the one factor that both you and your dental team can directly influence.
When overgrowth becomes severe enough to interfere with eating, speaking, or appearance, surgical removal of the excess tissue is an option. However, if the causative drug continues, the overgrowth frequently recurs after surgery, making ongoing oral hygiene even more critical for long-term management.