Tremor and shaking hands: causes, red flags and when to see a GP

The NHS defines a tremor as being unable to control shaking or trembling in part of your body. Parkinson's UK describes it as an uncontrollable, repetitive shaking movement, often affecting a hand or arm. Because everyone has a small physiological tremor, the question is whether the shaking is bigger than expected, new, one-sided, present at rest, or disabling.

Two descriptors matter to clinicians. A resting tremor occurs when the limb is relaxed, as when lying in bed or with the hand in the lap. An action tremor occurs when the limb is held against gravity or moving, for example writing, holding a cup or pouring a drink. Parkinson's UK describes both in Parkinson's disease, with resting tremor most common.

The NHS says some medicines and conditions can cause a tremor, in addition to the everyday triggers listed above. The table groups them.

A tremor is rarely an emergency on its own. The NHS says to see a GP if it is getting worse over time or affecting daily activities, so the doctor can make sure it is not caused by another condition. Features that suggest a neurological condition include a tremor that began on one side, a resting tremor with slowness or stiffness, a tremor with balance problems or falls, difficulty writing, loss of the sense of smell, constipation, sleep problems and mood changes, all of which the NHS lists among Parkinson's disease symptoms.

Some situations need prompt help. Shaking with sweating, hunger and confusion in someone with diabetes may be a hypo; the NHS describes treating it quickly with a fast-acting sugary drink or snack and calling 999 if the person is unresponsive. A tremor that comes on suddenly together with weakness, face drooping, speech problems or confusion is a stroke emergency: the NHS says to call 999 for any signs of a stroke. Parkinson's medicines should never be stopped suddenly, as NICE CKS warns that this may precipitate acute akinesia or neuroleptic malignant syndrome.

• A tremor that is getting worse over time or interfering with eating, writing or dressing.

• A resting tremor on one side with slow movements, stiffness or a shuffling walk.

• New tremor with weight loss, palpitations and heat intolerance.

• Tremor that began after a new medicine; do not stop it without advice.

• Sudden tremor with weakness, speech trouble or a drooping face: 999.

• Shaking with confusion or sweating in a person with diabetes.

The NHS says a GP may examine you and ask whether you have other symptoms, whether you are taking any medicine, and about your and your family's medical history, because some types of tremor run in families. Parkinson's UK describes the specialist assessment: asking you to relax your hands, arms and legs to see whether a tremor appears at rest, and to carry out a simple action such as drinking from a glass to see an action tremor, with questions about how often it happens, where, patterns and its effect on daily life, plus family history.

A mild tremor that is not caused by another condition does not usually need treatment, and the NHS says the GP may want to monitor it. You may be referred to a specialist for further tests if the tremor could be a symptom of a condition such as Parkinson's disease or multiple sclerosis. NICE CKS says people with suspected Parkinson's disease should be referred urgently, and untreated, to a movement disorders specialist.

Blood tests, particularly thyroid function, are used to look for a treatable cause; the NHS says an overactive thyroid is diagnosed after a GP arranges a blood test. Other tests, depending on the picture, include blood sugar, kidney and liver function. Parkinson's UK says that if a doctor is still unsure what is causing a tremor, a brain scan called a DaTSCAN may be helpful.

Parkinson's disease itself is a clinical diagnosis made by a specialist, as the NHS and CKS describe.

The NHS says that if a tremor is affecting your life the GP may prescribe medicine; it will not cure the tremor but often helps reduce the shaking, and may be taken all the time or only when needed, for example before a stressful situation. Injections to block nerves and relax muscles may be offered for a head or voice tremor, and brain surgery is rarely an option for a severe tremor not helped by medicine.

Parkinson's UK says medication and deep brain stimulation can treat tremor in Parkinson's, that getting active, planning ahead and reducing stress and anxiety may help, and that a Parkinson's nurse or occupational therapist can give practical tips, such as easy-grip cutlery. In the early stages some people reduce a hand tremor by squeezing a ball or pen. The National Tremor Foundation is a source of information the NHS lists.

A GP is the starting point. A neurologist or movement disorders specialist assesses suspected Parkinson's disease or essential tremor. An endocrinologist treats thyroid disease. A pharmacist or prescriber reviews medicines. Anyone with Parkinson's disease should tell the DVLA and their car insurer, as CKS advises.