Gabapentin and pregabalin

Gabapentin (for example, Neurontin) and pregabalin (for example, Lyrica) are closely related prescription medicines, sometimes called gabapentinoids. They are used for certain kinds of nerve pain and to help control certain seizures.

The FDA has approved standard gabapentin capsules, tablets and liquid for nerve pain after shingles and to help control certain seizures. Standard pregabalin capsules and liquid are approved for nerve pain after shingles, nerve pain from diabetes or spinal cord injury, fibromyalgia, and to help control certain seizures. ^{[7] [8]}

Other formulations have different approved uses. Horizant contains gabapentin enacarbil, which the body converts to gabapentin; it is not interchangeable with other gabapentin products. Lyrica CR is an extended-release form of pregabalin approved for nerve pain from diabetes and after shingles. It does not share all the approved uses of standard Lyrica. ^{[23] [24]}

For back pain, neck pain and sciatica (pain that travels down a leg from an irritated nerve), they are used “off-label.” That means the FDA has not approved them for this use, although prescribers are allowed to use them this way.

They are most often tried when pain seems to come from an irritated nerve, such as burning, shooting or electric pain down an arm or leg.

These medicines are thought to calm overactive nerves. They attach to nerve cells and reduce the release of chemical messengers that pass pain signals along.

They do not heal an irritated nerve or change what is pressing on it.

Before you start

Your prescriber will ask about your kidneys, breathing, other medicines, alcohol use, and any history of substance use or low mood.

Because the kidneys clear these medicines from the body, the dose depends on how well your kidneys work.

While you take it

Doses usually start low and go up slowly over days to weeks, to give your body time to adjust.

Dizziness and sleepiness are common. Until you know how the medicine affects you, avoid driving or using machinery.

Prescribers often plan a trial of several weeks, then check whether the benefit is worth the side effects. A simple record of your pain, sleep and activity can help with that decision.

Stopping

Stopping suddenly can cause withdrawal symptoms, such as trouble sleeping, nausea, headache, anxiety and sweating. In people who have seizures, stopping suddenly can bring on a seizure. When it is time to stop, prescribers usually lower the dose gradually.

If you already take one of these medicines and are unsure it helps, talk with your prescriber before making any change.

For sciatica, a well-designed trial of about 200 people found that pregabalin worked no better than a placebo (dummy pill) for leg pain, either at 8 weeks or at 1 year. People taking pregabalin had more side effects, especially dizziness.

Reviews that combined the studies on low back pain and sciatica reached the same conclusion: little or no benefit, and more side effects. An earlier review for the American College of Physicians found too little evidence to judge these medicines for low back pain. The newer reviews are more clearly negative.

For pain down the arm from an irritated nerve in the neck, there is very little good research.

These medicines are better studied for some other nerve pain conditions. In trials for nerve pain after shingles or from diabetes, about 3 to 4 in 10 people taking gabapentin had their pain cut at least in half, compared with about 1 to 2 in 10 taking a placebo. Even for those conditions, more than half of people do not get worthwhile relief.

Averages can hide differences between people. Some people with nerve-related back or leg pain feel these medicines help, but studies have not shown who they are.

Despite the weak evidence for back pain, prescriptions have grown in recent years, partly as an alternative to opioids.

Common

• Dizziness and sleepiness.
• Unsteady walking or clumsiness.
• Swelling of the feet, ankles or legs.
• Weight gain.
• Blurred vision or other vision changes.
• Trouble thinking clearly or concentrating, sometimes called “brain fog.”
• Tiredness and dry mouth.

In trials, about 6 in 10 people taking gabapentin had at least one side effect, compared with about 5 in 10 taking a placebo.

Less common

• Falls and injuries, especially in older adults or when combined with other medicines that cause drowsiness.
• Misuse and dependence, more often in people with a history of opioid or other substance use problems.
• Pregabalin is a federally controlled substance (Schedule V, the lowest level). Gabapentin is not federally controlled, but some states control or track it.
• Mood changes. Like other antiseizure medicines, these carry an FDA warning about an increased risk of suicidal thoughts or behavior.

Rare but serious

• Serious breathing problems. In 2019 the FDA warned that these medicines can dangerously slow breathing when combined with opioids or other medicines that cause drowsiness, in people with lung disease, and in older adults.
• In a large study, people taking gabapentin together with opioids were more likely to die of an opioid overdose than people taking opioids alone.
• Both medicines can rarely cause a serious allergic reaction, such as sudden swelling of the face, lips, tongue or throat. Gabapentin can also rarely cause a whole-body reaction with rash, fever and swollen glands.

Who needs extra care

Tell your clinician if you have kidney disease, heart failure, a lung condition, or a history of substance use or depression, or if you take opioids, muscle relaxants, benzodiazepines, sleep medicines or other medicines that cause drowsiness.

Guidance for older adults advises against combining these medicines with opioids.

Other downsides

• For back pain and sciatica, side effects are common while the chance of meaningful relief is low.

Get emergency care right away for slow, shallow or difficult breathing, blue-tinged lips, extreme sleepiness or trouble waking, swelling of the face, lips, tongue or throat, or a seizure. Contact your clinician right away about new or worse low mood. For thoughts of harming yourself, get emergency care, or call or text 988, the Suicide and Crisis Lifeline in the US.