Drug info

Modafinil

Wakefulness-promoting agent Prescription only (S4)

A tablet that helps people stay awake. Used for excessive daytime sleepiness from narcolepsy, sleep apnoea or shift work.

Brand names

How it works

Exactly how modafinil works isn’t fully known. It raises dopamine in the brain by blocking its reuptake and boosts other wake-promoting signals. It causes less of a “high” than amphetamines.

Used for

Side effects

How often, from the official product information. Bold = serious.

Very common more than 1 in 10

  • Headache
  • Nausea

Common 1 in 10 to 1 in 100

  • Nervousness or anxiety
  • Trouble sleeping
  • Dizziness or sleepiness
  • Low mood
  • Pins and needles
  • Back pain
  • Runny nose, sore throat or flu-like symptoms
  • Diarrhoea, constipation, indigestion or dry mouth
  • Less appetite
  • Fast heartbeat, palpitations or flushing
  • Raised blood pressure
  • Chest pain
  • Abnormal liver tests

Rare 1 in 1,000 to 1 in 10,000

  • Agitation, aggression, psychosis, mania or suicidal thoughts
  • Tremor or unusual movements
  • Rash, acne, eczema or itch

Very rare fewer than 1 in 10,000

  • Serious skin reactions (SJS, TEN, DRESS)
  • Anaphylaxis or angioedema
  • Multi-organ allergic reaction, seizures
  • Heart rhythm problems or reduced heart blood flow
  • Sweating, swelling

Get help urgently if

Good to know

Information only. Not a recommendation or endorsement of any product. Whether a medicine suits you depends on your health and other medicines, so talk to your doctor or pharmacist. In an emergency, call 000.

More information

Reviewed October 2026.