Baclofen is a muscle relaxant and antispastic, used mainly for spasticity from multiple sclerosis, and it comes with two facts worth knowing before the first dose. The first is that drowsiness is common rather than occasional. The second is that hallucinations and seizures have occurred on abrupt withdrawal of baclofen, which is why it is never a medicine to simply stop.

Both facts are on the label, and both are the kind of thing people discover the hard way if nobody tells them in advance.

Key takeaways

  • It treats spasticity, and the label names relief of flexor spasms and associated pain, clonus and muscular rigidity in multiple sclerosis.
  • Drowsiness is common. The label reports transient drowsiness in 10 to 63% of people, and in one controlled study of 175 patients it occurred in 63% on baclofen against 36% on placebo.
  • Never stop it abruptly. Hallucinations and seizures have occurred on abrupt withdrawal.
  • It works best where spasticity is reversible, so that treatment aids in restoring residual function.
  • Some people use their spasticity. Where stiffness is what keeps someone upright or walking, reducing it can make function worse, not better.
  • Epilepsy needs monitoring. Deterioration in seizure control and EEG has been reported occasionally.
  • Dose is worked up gradually, which is how the drowsiness is managed.

What is spasticity, and what does baclofen do about it?

Spasticity is involuntary muscle stiffness and spasm from a problem in the nervous system, and baclofen reduces it.

The label describes baclofen as a muscle relaxant and antispastic, useful for the alleviation of signs and symptoms of spasticity resulting from multiple sclerosis, particularly for the relief of flexor spasms and concomitant pain, clonus, and muscular rigidity.

Those four things are worth separating, because people experience spasticity differently:

  • Flexor spasms, sudden involuntary bending movements of a limb.
  • Pain that comes with those spasms.
  • Clonus, rhythmic involuntary contractions, often at the ankle.
  • Muscular rigidity, persistent stiffness that makes movement hard.

Baclofen is also used for spasticity from spinal cord injury and other spinal conditions. It treats the spasticity, not the underlying condition causing it.

Who does it help most?

People whose spasticity is reversible, where reducing it restores function rather than removing support.

The label puts a condition on its usefulness that is easy to skim past: patients should have reversible spasticity so that baclofen treatment will aid in restoring residual function.

The counterpart is the more important warning. Baclofen should be used with caution where spasticity is utilised to sustain upright posture and balance in locomotion, or whenever spasticity is used to obtain increased function.

That is a genuinely counterintuitive point. Some people with weak legs are standing and walking partly because their muscles are stiff. Take the stiffness away and the weakness underneath is exposed, so they become less mobile rather than more. This is why baclofen is titrated carefully with attention to what happens to function, not just to how the muscles feel.

If you start baclofen and find that walking or transferring becomes harder even though the spasms have improved, that is important information for your prescriber rather than something to push through.

How likely is the drowsiness?

Much more likely than most side effects, and the label gives a number.

The most common side effect is transient drowsiness, reported at 10 to 63%. The label cites one controlled study of 175 patients in which transient drowsiness was observed in 63% of those receiving baclofen compared with 36% of those on placebo.

Two things follow. The word transient matters: for many people the drowsiness settles as they get used to the medicine, which is why doses are usually started low and increased gradually. And the placebo figure matters too: some of what people attribute to a medicine belongs to the underlying condition, though the difference between 63% and 36% is real.

Practically:

  • Do not drive or operate machinery until you know how it affects you.
  • Expect the first days and each dose increase to be the sleepiest points.
  • Take care with alcohol and with other medicines that cause drowsiness.
  • Tell your prescriber if the drowsiness is not settling, since the schedule can often be adjusted.

Why is stopping suddenly dangerous?

Because hallucinations and seizures have occurred on abrupt withdrawal.

This is the single most important safety fact about baclofen and it is stated plainly on the label under Abrupt Drug Withdrawal.

The practical consequences are worth thinking through in advance, because the usual way people stop a medicine abruptly is not by deciding to:

  • Running out. Order a repeat before you are down to the last few days, particularly around travel or public holidays.
  • Travel. Carry enough for the trip plus a margin, in your hand luggage.
  • Deciding it is not working. If you want to come off it, that is a conversation about tapering, not a decision to implement.
  • Illness. If you cannot keep tablets down, tell a doctor rather than simply missing doses.

Withdrawal should be gradual and supervised. If you have missed several doses already, contact your prescriber rather than restarting at your previous dose on your own.

In patients with epilepsy, the label advises that the clinical state and EEG should be monitored at regular intervals, since deterioration in seizure control and EEG has been reported occasionally in patients taking baclofen.

What else should I raise with a prescriber?

Kidney function, other sedating medicines, and what you use your muscle tone for.

Points worth raising before or shortly after starting:

  • any kidney problems, since dose may need adjusting
  • epilepsy or a history of seizures
  • other medicines that cause drowsiness, including some antihistamines such as hydroxyzine
  • whether you rely on stiffness to stand, transfer or walk
  • mental health history, given the withdrawal effects described above

Related medicines in this catalogue include tizanidine and methocarbamol, which are also used for muscle spasm but are not interchangeable with baclofen or with each other.

Do and don’t

Do:

  • Take it exactly as prescribed, and expect the dose to be built up gradually.
  • Order repeats early so you never run out.
  • Carry enough on trips, in hand luggage.
  • Report if walking or transferring gets harder even as spasms improve.
  • Tell your prescriber about other sedating medicines.

Don’t:

  • Don’t stop it suddenly, ever, or let yourself run out.
  • Don’t drive until you know how the drowsiness affects you.
  • Don’t increase the dose yourself to get more effect.
  • Don’t assume a muscle relaxant prescribed for someone else does the same thing.
  • Don’t combine it casually with alcohol or other sedatives.

Frequently asked questions

Is baclofen a painkiller? Not directly. It is a muscle relaxant and antispastic, and it relieves the pain that comes with flexor spasms by reducing the spasms themselves. It does not act on pain the way an analgesic does.

Will the drowsiness go away? The label describes the drowsiness as transient, and for many people it settles as the body adjusts, which is why doses are increased gradually. If it does not settle, that is a reason to speak to your prescriber rather than to stop.

What if I have missed a few doses? Contact your prescriber rather than resuming your previous dose independently. Abrupt withdrawal is associated with hallucinations and seizures, and restarting safely after a gap is a clinical decision.

Where to go next

The pain and anti-inflammatories and neurology categories list what is stocked here, and the ingredients index maps active ingredients to the brands containing them. If heat is a factor in your storage arrangements, that is covered in storing medicine in a Gulf summer.

MedicForce option: our listings show active ingredient and strength, which matters for a medicine whose dose is built up in steps.

Label statements quoted above, including the withdrawal warning and the drowsiness figures, are from the approved product information for baclofen.