Primidone is an older anticonvulsant that turned out to be one of the two most effective medications for essential tremor — the other being propranolol. Both are considered first-line, and both are rated Level A (established as effective) in the American Academy of Neurology's evidence-based guideline (Zesiewicz et al., Neurology, 2011). Its effectiveness for tremor was confirmed in double-blind trials decades ago (Findley & Cleeves, JNNP, 1985), and it works whether or not you're already taking propranolol. For people who can't take a beta-blocker — for example because of asthma, or because propranolol lowered their blood pressure or mood too much — primidone is often the first choice instead. It's worth knowing that in the body primidone is partly converted to phenobarbital, an older sedative, which is why drowsiness is its signature effect and why it interacts with certain other medications — both facts that shape how it's started and dosed.

Here's the honest version of the start. Primidone is known for an acute first-dose reaction: a bout of nausea, dizziness, unsteadiness, and heavy drowsiness that can hit on the very first tablet or two, before your body adjusts. It can feel alarming enough that people quit after one dose, assuming they can't tolerate the drug. In reality it is usually temporary, and it is largely avoidable with how the medication is introduced.

That's why primidone is almost always started at a very low dose, taken at bedtime so you sleep through the worst of it, and then increased in small steps over days to weeks. Taking the first doses at night, going slowly, and not driving until you know how it affects you all make the start far more manageable. It helps to plan the first few days for a time when you don't have to work, drive, or be sharp — a weekend, say — so a groggy morning is an inconvenience rather than a problem. And it's worth setting the expectation with yourself in advance that the first day or two may feel rough on purpose, so that if it does, you recognise it as the known, passing start rather than a sign the medication is wrong for you.

One of the more reassuring facts about primidone is that you may not need much of it. A controlled study found primidone reduced tremor across a wide dose range — from 50 up to 1,000 mg a day — and, importantly, that low doses were as effective as high doses (Koller & Royse, Neurology, 1986). Many people with essential tremor get good control on modest amounts, well below the levels used to treat epilepsy. The practical implication is that the goal is the lowest dose that steadies your hands acceptably, reached gradually — not the highest dose you can tolerate. It also means the schedule is worth respecting: rushing the increase is what turns a manageable adjustment into a miserable one, while a patient, stepwise build-up gives your body time to accommodate the sedative effect. If a particular step up brings back the drowsiness or unsteadiness, that's usually a signal to hold or slow down rather than to abandon the medication — a conversation to have with your prescriber.

Past the first weeks, primidone is generally well tolerated at the low doses used for tremor. The effect people most often notice is some drowsiness or fatigue, which is one reason the dose is kept as low as it needs to be and often weighted toward the evening. Less commonly, people report unsteadiness, low mood, nausea, or a foggy, slowed feeling in concentration and memory — the latter being a common reason people ask their doctor to lower the dose or switch. These effects, when they happen, are worth taking seriously rather than pushing through indefinitely: because low doses are often as effective as high ones, there is usually room to find a level that steadies the tremor without leaving you feeling dulled. As with any medication, the balance that matters is whether the improvement in your tremor is worth the side effects you actually experience — something to reassess with your doctor rather than simply endure.

For essential tremor, primidone is one of the most effective medications available. Beyond its Level A rating, the numbers are encouraging: in one study, a dose of primidone reduced tremor by 54% to 69% in most of the patients tested (Seyfert & Honé, J Neurol, 1988), and a separate controlled study found it reduced tremor more than propranolol did (Koller & Royse, Neurology, 1986). That doesn't mean it's better for everyone — response to tremor medication is individual, and some people do better on propranolol, or on the two combined. Combining the two first-line drugs is a common next step when either alone isn't enough, since primidone has been shown to reduce tremor even in people already on propranolol (Koller & Royse, Neurology, 1986). But it does mean primidone is a genuinely strong option, and the rough start is worth weathering to find out whether you're one of the many people it helps.

The mindset that gets people through primidone is simple: expect the beginning to be the hardest part, and judge the drug on how you feel once you're settled, not on the first dose. Give the low-and-slow schedule a fair chance, take the early doses at night, and don't drive until you know your response. Call your doctor if the acute reaction is severe or doesn't settle after the first couple of weeks, if drowsiness is interfering with daily life, or if you're not getting enough tremor benefit at a reasonable dose — any of which is a reason to adjust the plan, not to stop the medication on your own.