Key takeaways:
Horizant and Gralise are gabapentin medications that last longer in the body than immediate-release gabapentin.
Horizant and Gralise are both effective for nerve pain from shingles. Horizant also treats restless leg syndrome. But neither medication is approved to treat other types of pain.
Horizant and Gralise are both available as brand-name medications. But you can also find Gralise as a lower-cost generic. GoodRx can help you find ways to make your prescription more affordable.
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Gabapentin is a medication that treats many medical conditions. It comes in an immediate-release (IR) formulation (Neurontin). And it’s available as extended-release (ER) tablets under the brand names Horizant and Gralise.
Horizant and Gralise were FDA approved in 2011. These medications are longer-acting than IR gabapentin, so you don’t have to take them as often throughout the day. These ER forms may also be less likely to cause side effects than the IR versions.
But how do you choose between Horizant and Gralise? We’ll break down some key differences between these gabapentin forms. This will help you better understand your options so you can make the choice that’s right for you.
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Horizant vs. Gralise at a glance
In the following table, we’ve compared notable features of Horizant and Gralise.
Active ingredient | Gabapentin enacarbil (a prodrug that converts to gabapentin after you take it) | Gabapentin |
FDA-approved uses | • Restless leg syndrome (RLS) in adults • Postherpetic neuralgia (nerve pain after shingles) in adults | • Postherpetic neuralgia in adults |
Product availability | Brand-name-only tablet | Brand-name and generic tablets |
Formulations | ER tablets: • 300 mg • 600 mg | ER tablets: • 300 mg • 450 mg • 600 mg • 750 mg • 900 mg |
Typical dosages | • For RLS: 600 mg once daily around 5PM • For postherpetic neuralgia: 600 mg once in the morning for 3 days, then 600 mg twice daily | • Initiation: 300 mg once daily with your evening meal • Maintenance: increased gradually up to 1,800 mg once daily with your evening meal over about 2 weeks |
Common side effects | • Dizziness • Sleepiness • Headaches • Fluid buildup (swelling) • Irritability • Dry mouth | • Dizziness • Sleepiness • Fluid buildup • Dry mouth |
Below, we’ll cover six ways that Horizant and Gralise compare in more detail.
1. Horizant and Gralise have different active ingredients, but work the same way
Horizant is a brand-name-only, ER tablet that contains gabapentin enacarbil, a prodrug of gabapentin. Gabapentin enacarbil is more easily absorbed by your gastrointestinal (GI) tract than gabapentin itself. As it’s absorbed, your body converts the prodrug into active gabapentin. This helps provide steadier gabapentin levels for a longer period of time.
Gralise is another gabapentin product, but it’s not a prodrug like Horizant. Instead, Gralise stays in your stomach and slowly releases gabapentin into your GI tract throughout the day. It comes as an ER tablet in both brand-name and generic formulations.
These differences may matter if you take another medication, such as a glucagon-like peptide-1 (GLP-1) agonist, or have a condition that affects how substances move through your stomach.
How do gabapentin products work for nerve pain?
We don’t know exactly how gabapentin works to relieve nerve pain.
That said, the structure of gabapentin is similar to a brain chemical called gamma-aminobutyric acid (GABA). GABA slows down nerve activity and relaxes the body. This may be how gabapentin relieves nerve pain.
2. Horizant and Gralise are approved for different uses
Horizant is FDA approved to treat postherpetic neuralgia (nerve pain from shingles) and restless leg syndrome (RLS) in adults.
Gralise is only approved to treat postherpetic neuralgia in adults.
Add GoodRx as a trusted source on GoogleAdd GoodRx as a trusted source3. Horizant and Gralise have different recommended dosages
Horizant and Gralise have different recommended dosages. And it’s important to note that, even at the same doses, Horizant and Gralise aren’t interchangeable. This means that taking 600 mg of Horizant is not the same as taking 600 mg of Gralise.
Horizant
When Horizant is taken for postherpetic neuralgia, the typical starting dosage is 600 mg every morning with food for 3 days. Then, the dosage is usually increased to 600 mg twice daily with food.
When Horizant is prescribed for RLS, the usual dosage is 600 mg once daily at around 5PM with food.
Gralise
For postherpetic neuralgia, your healthcare professional will likely start you on a low dose of Gralise (300 mg) and slowly raise it over the course of 2 weeks or more (up to 1,800 mg). Gralise comes as a “starter pack” that contains a guide to help you with the initial dosage schedule.
Regardless of your dose, Gralise is taken once a day with your evening meal.
4. Horizant and Gralise are both effective options for treating nerve pain
Clinical studies have shown that Horizant and Gralise effectively treat nerve pain. We’ll take a look at how well they work for their approved uses below.
Postherpetic neuralgia
One clinical trial compared various doses of Horizant with a placebo (a pill with no medication in it). After 12 weeks of treatment, over 300 people rated their pain. Horizant, at all doses, was more effective at improving pain than a placebo. And a 1,200 mg dose of Horizant was just as effective as higher doses.
Another clinical trial looked at over 450 people taking either Gralise 1,800 mg daily or a placebo pill for 8 weeks. People taking Gralise had more improvement in pain than the people taking a placebo.
There isn’t much research that compares Horizant and Gralise for postherpetic neuralgia. But it’s been found that Horizant leads to more steady gabapentin levels in the body over the course of a day. This means Horizant may provide more consistent pain relief than Gralise for some people.
RLS
Horizant was studied as a treatment for RLS in two 12-week clinical trials. Both Horizant 600 mg and 1,200 mg were studied. Both doses were better than a placebo at relieving symptoms of RLS.
Other types of pain
There’s not much research on Horizant and Gralise for other types of pain. Some small studies found that Gralise may be effective for other types of pain, such as pain after an amputation or pain caused by spinal stenosis or fibromyalgia. But these were small studies that weren’t well designed. So they don’t provide enough information about whether Gralise can treat these types of pain.
However, another study looking at Gralise for nerve pain from diabetes found that it did lower pain symptoms. This was a slightly larger study of nearly 150 people. And it was a randomized controlled trial, the best type of study to look for cause and effect. So there’s a likelihood that Gralise may help with this type of nerve pain.
Keep in mind: IR gabapentin is recommended as a first-choice treatment for some types of nerve pain, such as diabetic nerve pain. But how well it works for other types of pain is unclear. It also isn't considered the best option for certain types of chronic pain, including back pain.
Are gabapentin products approved for chronic pain?
No, gabapentin products are not approved for chronic pain. Chronic pain is defined as pain that is consistent or comes and goes for at least 3 months.
While gabapentin might be prescribed off-label to treat different types of pain, there’s not much evidence that it is effective at treating chronic pain. This is especially true for chronic pain that isn’t nerve-related.
5. Horizant and Gralise have similar side effects
Horizant and Gralise can cause many of the same side effects, including:
Dizziness
Sleepiness
Swelling in the extremities (e.g., arms, feet, or ankles)
Dry mouth
In addition to the above, Horizant may cause headaches, irritability, and decreased sexual desire. Weight gain and urinary tract infections have been reported with Gralise. Keep in mind that the likelihood of you experiencing side effects from either medication can depend on the dose you take.
Serious side effects of Horizant and Gralise
Some side effects of Horizant and Gralise can be more serious and require medical attention. However, these aren’t as common as the side effects discussed above.
Rare but serious side effects of Horizant and Gralise include:
Suicidal thoughts or behavior: Horizant and Gralise may increase the risk of suicidal thoughts or behavior. These mood-related changes can happen as early as 1 week after starting either medication. Talk to a healthcare professional if you notice new or worsening depression or other mood changes.
Trouble with activities that require focus: Horizant and Gralise can cause dizziness and drowsiness, which may make certain activities, such as driving, unsafe. When starting either medication or increasing your dose, don’t drive or do other activities that require alertness until you know how the medication affects you.
If you or someone you know is having thoughts of suicide, you’re not alone, and help is available. Call the National Suicide Prevention Lifeline at 988, or text “HOME” to 741-741 to reach the Crisis Text Line.
6. Horizant and Gralise have different interactions to consider
Horizant and Gralise may interact with certain medications. Most notably, Horizant and Gralise, like all forms of gabapentin, can be dangerous when combined with other sedating medications and substances. This includes opioids, benzodiazepines, and alcohol. This interaction can cause side effects such as extreme sleepiness and, in serious cases, trouble breathing and overdose.
It’s also best to avoid sleep medications such as zolpidem (Ambien) while taking Horizant or Gralise. Even over-the-counter medications that cause drowsiness, such as diphenhydramine (Benadryl), may not be safe.
Make sure your prescriber and pharmacist know about any medications or supplements you’re taking before you start Horizant or Gralise. They can check for possible interactions to make sure gabapentin is safe for you to take.
Can you switch from Gralise to Horizant (or vice versa)?
You can switch from Gralise to Horizant (or vice versa), but only with the help of your prescriber. As mentioned, Horizant and Gralise aren't interchangeable, even at the same milligram dose. That's because they release gabapentin into your body differently. So 600 mg of one doesn't have the same effect as 600 mg of the other.
If your prescriber wants you to switch from one of these medications to the other, they'll likely have you lower the dose of your current medication while starting the new one. This gradual switch can help lower the risk of withdrawal symptoms, such as headaches, nausea, and diarrhea. Stopping either medication too quickly may also lead to seizures.
Only make changes to your medication regimen under your prescriber's guidance. Your prescriber will instruct you on how to slowly switch medications if necessary.
How to save on Horizant and Gralise
Horizant and Gralise are available as brand-name medications. But you can also find Gralise as a lower-cost generic. GoodRx can help you navigate between GoodRx savings, manufacturer copay cards, and patient assistance programs to save money on your prescription:
Save with GoodRx. GoodRx could help you save over 75% off the average retail price of the generic version of Gralise. At certain pharmacies, the price for 90 tablets of generic Gralise 600 mg may be as low as $485.40 with a free GoodRx discount.
Save with GoodRx Companion. You can access discounted prescription medications with a GoodRx Companion subscription. Over 200 medications are available for free, with hundreds more for under $10. The program also includes benefits to help you cut your self-pay costs, such as lower prices for online care visits, discounts on dental care, and other health service savings.
Save with a copay savings card. If you have commercial insurance, you may be eligible to pay as little as $0 monthly for Horizant or $20 monthly for Gralise using a savings card from the manufacturer.
Save with a patient assistance program. If you’re uninsured or underinsured, you may be eligible for Horizant’s patient assistance program, which offers the medication for as little as $55 per prescription.
Frequently asked questions
No, gabapentin isn’t a narcotic. The term “narcotic” usually refers to opioids, which act on pain receptors and can lead to dependence. Gabapentin works in a different way. It calms down extra-active nerve signals in your brain and spinal cord.
Still, gabapentin isn’t risk-free. Some states treat gabapentin as a controlled substance because it carries a risk of misuse and dependence. Gabapentin can also raise the risk of overdose when combined with opioids. It’s best to discuss the risks and benefits of gabapentin with a healthcare professional to determine if it’s a good option for you.
For most people, Horizant and Gralise cause drowsiness. But Horizant can sometimes cause trouble sleeping, especially at higher doses. This wasn’t a common side effect of Gralise in clinical studies, but it can happen. Insomnia can also occur if you stop taking either medication too suddenly, so always talk to your prescriber before stopping either one.
In general, you shouldn’t take gabapentin medications if you are living with moderate-to-severe kidney problems, have a history of substance misuse, or are 65 or older. It’s also best to avoid Horizant and Gralise if you take other sedating or interacting medications. These combinations can increase the risk of gabapentin side effects.
What’s more, don’t take Horizant or Gralise if you’re allergic to gabapentin or any of their inactive ingredients. Speak with your prescriber to see if Horizant or Gralise is a safe option for you.
No, gabapentin isn’t a narcotic. The term “narcotic” usually refers to opioids, which act on pain receptors and can lead to dependence. Gabapentin works in a different way. It calms down extra-active nerve signals in your brain and spinal cord.
Still, gabapentin isn’t risk-free. Some states treat gabapentin as a controlled substance because it carries a risk of misuse and dependence. Gabapentin can also raise the risk of overdose when combined with opioids. It’s best to discuss the risks and benefits of gabapentin with a healthcare professional to determine if it’s a good option for you.
For most people, Horizant and Gralise cause drowsiness. But Horizant can sometimes cause trouble sleeping, especially at higher doses. This wasn’t a common side effect of Gralise in clinical studies, but it can happen. Insomnia can also occur if you stop taking either medication too suddenly, so always talk to your prescriber before stopping either one.
In general, you shouldn’t take gabapentin medications if you are living with moderate-to-severe kidney problems, have a history of substance misuse, or are 65 or older. It’s also best to avoid Horizant and Gralise if you take other sedating or interacting medications. These combinations can increase the risk of gabapentin side effects.
What’s more, don’t take Horizant or Gralise if you’re allergic to gabapentin or any of their inactive ingredients. Speak with your prescriber to see if Horizant or Gralise is a safe option for you.
The bottom line
Gralise and Horizant are extended-release forms of gabapentin. Both products are FDA approved to treat postherpetic neuralgia (nerve pain from shingles). Horizant is also approved to treat restless leg syndrome. Horizant is taken 1 to 2 times a day, and Gralise is usually taken once a day in the evening.
Both medications are effective at treating postherpetic neuralgia, and Horizant is effective at treating restless leg syndrome. But these medications haven’t been directly compared. And it’s unclear how effective gabapentin products are for other types of pain.
The most common side effects of Horizant and Gralise are dizziness and tiredness. They can also cause more serious side effects, such as suicidal thoughts and behavior. Your prescriber can help you find the right form of gabapentin for your needs based on your medical history.
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