Cyclizine is mainly used to prevent and treat nausea, vomiting, and dizziness, especially from motion sickness, vertigo, and after surgery or certain medicines like opioids or chemotherapy.

What is cyclizine?

Cyclizine is an antihistamine that also acts as an anti-sickness (antiemetic) medicine. It works by blocking histamine signals in the brain areas that trigger nausea and vomiting, and it also has anticholinergic (drying/relaxing) effects.

What is cyclizine used for?

Common medical uses include:

  • Nausea and vomiting from:
    • Motion sickness (travel sickness in cars, boats, planes)
    • Vertigo and inner ear problems such as MĂŠnière’s disease
    • Post‑operative sickness after general anaesthetic
    • Medicines that cause nausea (for example some opioids, cancer treatments, or radiotherapy)
  • Dizziness associated with motion sickness or vertigo.
  • Sometimes in pregnancy-related severe vomiting (hyperemesis gravidarum), usually under specialist supervision and often off-label.

In some clinical and non-clinical settings, it has been misused to enhance or “potentiate” the effects of opioids, which is an off‑label and risky use.

How does cyclizine work?

  • Blocks H1 histamine receptors in the vomiting centre and balance (vestibular) pathways in the brain.
  • Also blocks some muscarinic (acetylcholine) receptors, which contributes to its anti-sickness effect but also to side effects like dry mouth and blurred vision.
  • Typically starts working in about 30 minutes, with its effect lasting around 4–6 hours.

Forms and how it’s given

Depending on the country and product, cyclizine may be available as:

  • Tablets (often 50 mg)
  • Injection (e.g., cyclizine lactate for IV or IM use, commonly in hospital)
  • Sometimes suppositories (rectal) in some settings

Doses and schedules vary by age, indication, and route, so they should follow a doctor’s or pharmacist’s instructions and the patient information leaflet.

Common side effects and cautions

Frequent side effects include:

  • Drowsiness or tiredness
  • Dry mouth, dry nose or throat
  • Blurred vision
  • Constipation, difficulty passing urine
  • Headache or dizziness

Because of its anticholinergic and sedative effects, extra care is needed if someone has:

  • Glaucoma (high eye pressure)
  • Enlarged prostate or urinary retention
  • Bowel obstruction or severe constipation
  • Asthma or chronic lung disease
  • Certain heart, liver, or kidney conditions
  • Epilepsy, confusion, or dementia

It can interact with alcohol, sleeping tablets, strong painkillers (opioids), and other medicines that cause drowsiness or have anticholinergic effects. Overuse or high doses can increase the risk of serious side effects, including agitation, hallucinations, heart rhythm problems, and breathing issues, and in some reports it has been involved in substance misuse.

Cyclizine is usually avoided or used with caution in pregnancy unless a specialist advises otherwise, and it should not be used in children below the minimum age recommended in local guidelines.

Quick safety checklist

If you are wondering whether cyclizine is suitable in a real‑life scenario, it is important to:

  1. Check what is causing the nausea (travel, infection, medication, pregnancy, etc.).
  2. Review other medicines you or the person is taking, especially sedatives or opioids.
  3. Check for medical conditions like glaucoma, urinary problems, bowel blockage, serious heart disease, or severe liver/kidney disease.
  4. Avoid driving or operating machinery until you know how sleepy it makes you.
  5. Speak to a doctor, pharmacist, or nurse before starting it, especially for children, older adults, pregnancy, or long‑term use.

Information gathered from public forums or data available on the internet and portrayed here.