Studies suggest that there may be serious neurological side effects of Dilantin in adults and children with prolonged use.

Dilantin, and its generic form phenytoin, are seizure medications often prescribed to adults and children who experience epileptic seizures – including partial complex seizure and grand mal seizures. Dilantin may also be given to patients before and after brain surgery to prevent seizures associated with the procedure.

There are other uses for Dilantin, including the treatment of mental health conditions. Conditions treated by the drug include anxiety, depression, bipolar disorder, aggressive behavior, Tourette’s syndrome, and ADHD.

The drug prevents seizures by stabilizing the neurological response when the brain is stimulated by environmental events such as flashing lights.

During a seizure, sudden abnormal brain activity can cause a variety of symptoms including convulsions. Most seizures last between 30 seconds to a minute, but are considered an emergency if they last over 5 minutes or the person does not wake up after, according to Medline Plus. Seizures can cause neurological damage if left untreated, which is why treating seizure conditions is of the utmost importance.

Although Dilantin can be helpful in treating seizures, studies have revealed concerning side effects of the seizure medication in adults and children which may outweigh the benefits of the medication.

One of the more alarming side effects reported by studies is cerebellar atrophy, a degenerative condition affecting the cerebellum. When the cerebellum is healthy and functioning as it should, it helps with movements and coordination.

However, when the cerebellum is damaged, it can cause symptoms similar to those of a stroke – tremors, shaking, unstable eye movements, slurred or slow speech, memory loss, and cerebellar ataxia (movement abnormalities including staggering, broadened stance, and abnormal gait).

The cerebellum can be damaged by a variety of conditions including brain injury, stroke, multiple sclerosis, tumors, seizures, and cerebellar disorders. However, studies have shown that the condition may be among side effects of Dilantin in adults and children.

In 1994, a Dilantin study aimed to determine the cause of cerebellar atrophy in patients with partial epilepsy taking Dilantin to treat the condition. However, the study also wanted to consider the fact that seizures (which Dilantin is prescribed to treat) can also cause cerebellar atrophy.

The researchers studied 36 patients treated long term with phenytoin who had MRI testing done after complaining of headache and dizziness and compared outcomes with a control group.

“Cerebellar atrophy was significantly more pronounced in patients than in controls. No correlation was found between cerebellar atrophy and variables reflective of seizure severity or degree of phenytoin exposure,” the study found.

“Cerebellar atrophy may be seen in phenytoin-exposed patients with epilepsy in the absence of generalized tonic-clonic seizures or preexistent brain damage. Whether it is the phenytoin or the seizures that play the primary etiologic role remains unanswered.”

Further studies have explored the cerebellar atrophy and Dilantin link deeper. Researchers have reported that the side effect is not limited to adults and can also affect children. Other research noted that the side effect typically occurs when blood serum levels are outside the normal recommended therapeutic range, although it can occur when blood serum levels are normal.

Dilantin and Generic Phenytoin May Absorb Differently

According to Epilepsy.com, the brand names of phenytoin include both Dilantin and Phenytek, which is an extended-release form of the medication.

In some patients who change from brand-name Dilantin or Phenytek to generic phenytoin, an increase in the number of seizures or other side effects may occur. This is due to different generic forms of phenytoin having different non-active fillers that can affect the absorption rate or metabolism of the active drug.

Some patients who start taking Dilantin by taking a generic form and staying with that generic form may use generics successfully.

The accuracy of the dose is important because phenytoin is a very potent drug. Research indicates it works by locking the frequency-dependent, use-dependent and voltage-dependent neuronal sodium channels that upon firing too frequently, cause seizures. When a patient takes a therapeutic level of phenytoin, the firing patterns are normalized. With too much phenytoin in the body, a toxic level may result in the impairment of the function of healthy neurons.

Indications of too much phenytoin may include the following symptoms:

• Extreme fatigue, sedated state
• Memory impairment
• Slurred speech
• Fast, darting eye movements (nystagmus)
• Coordination problems
• Confusion
• Dizziness
• Headache

One of the most common side effects is overgrowth of the gums. The gums start to cover the teeth, a side effect known as gingival hyperplasia that may affect up to 40 percent of phenytoin patients who take the drug over a long period of time. The side effect is most often dose-related and seems to affect children more often than adults.

Other side effects may include an increased coarseness of facial features, acne and increased male-pattern hair growth on the face, chest, and back.