Medazine contains cyclizine 50 mg, an antihistamine used to prevent and treat nausea, vomiting and motion sickness. It also relieves vertigo and the nausea of inner-ear disorders. It causes drowsiness, so it should not be taken before driving.
What is Medazine?
Medazine contains cyclizine hydrochloride 50 mg, an antihistamine with strong anti-nausea properties. It is a Schedule 2 medicine, also sold as Valoid.
Cyclizine blocks histamine H1 receptors and has antimuscarinic activity — and where it does this matters. It acts on the vestibular system in the inner ear and on the vomiting centre in the brainstem, both of which rely on histamine and acetylcholine signalling.
That is why an antihistamine treats sickness. Motion sickness arises from a mismatch between what your inner ear senses and what your eyes see; the vestibular system signals that conflict to the vomiting centre, and cyclizine interrupts the message.
Which anti-sickness medicine is right depends on the cause of the nausea, because different pathways drive it:
- Motion, vertigo and inner-ear causes → antihistamines such as cyclizine.
- Gut causes, or slow stomach emptying → metoclopramide, as in Adco-Contromet.
- Chemotherapy or post-operative nausea → ondansetron and related medicines.
Matching the medicine to the mechanism works considerably better than trying whichever is at hand.
What is Medazine commonly used for?
- Motion sickness — car, bus, boat, aeroplane — both preventing and treating it.
- Nausea and vomiting from various causes.
- Vertigo, and nausea from inner-ear disorders including labyrinthitis and Ménière’s disease.
- Post-operative nausea and vomiting.
- Nausea from migraine.
- Nausea in palliative care, in some circumstances.
For motion sickness, timing is what makes it work. Take it before travelling — typically about an hour beforehand — rather than once you already feel sick. Cyclizine blocks the signal; it cannot easily reverse nausea that is already established, and a stomach that has stopped emptying absorbs a tablet poorly.
Non-medicine measures genuinely help, and reduce how much you need: sit where motion is least (over the wing on a plane, midships on a boat, in the front seat of a car), look at the horizon rather than a screen or book, keep fresh air moving, and avoid heavy or greasy food before travelling.
Nausea and vomiting need a cause. Persistent vomiting, or vomiting with abdominal pain, headache, fever or dizziness, needs assessment rather than repeated symptom treatment.
How Medazine fits into this medicine category
| Group | Examples | Best for |
|---|---|---|
| Antihistamine antiemetics | Cyclizine (Medazine, Valoid), promethazine | Motion sickness, vertigo, inner-ear nausea |
| Dopamine antagonists | Metoclopramide (Adco-Contromet) | Gut causes, slow stomach emptying |
| 5-HT3 antagonists | Ondansetron | Chemotherapy, post-operative nausea |
| Antimuscarinics | Hyoscine hydrobromide | Motion sickness, as patches or tablets |
| Antispasmodics | Hyoscine butylbromide (Buscopan) | Cramping, not nausea |
Note the last row: hyoscine butylbromide relieves gut cramping and does not cross into the brain, while hyoscine hydrobromide does and is used for motion sickness. The names are similar and the uses are not. See the digestive, stomach and nausea medicines hub.
What to check before using Medazine
Take it before travelling, not after nausea starts.
Do not drive until you know how it affects you. Drowsiness is common and is the main practical limitation.
Do not drink alcohol with it — the sedation compounds.
Speak to a pharmacist or doctor if:
- You have glaucoma, particularly narrow-angle.
- You have an enlarged prostate or difficulty passing urine.
- You have epilepsy.
- You have liver or kidney disease.
- You have heart failure or a heart rhythm problem.
- You have severe asthma or COPD — antimuscarinic effects thicken secretions.
- You are pregnant or breastfeeding. Cyclizine is used in pregnancy sickness in some circumstances, but confirm with your clinician.
- You are older, where confusion, falls and urinary retention are markedly more likely.
- The medicine is for a child — check the right form and amount.
- You take other sedating medicines, another antihistamine, or another antimuscarinic medicine.
Follow the pack instructions. This page does not set doses.
Possible cautions and when to ask a pharmacist or doctor
Drowsiness is expected, not a surprise. Plan around it.
Dry mouth, blurred vision, constipation and difficulty passing urine are common antimuscarinic effects.
In older adults, use it cautiously. Confusion, falls and urinary retention are genuine risks with this class, and the threshold for choosing something else should be lower.
Cyclizine is misused by injection for its euphoric effects at high doses, particularly alongside opioids. That is dangerous and can cause hallucinations, seizures and cardiac effects. Take only the amount prescribed, by mouth.
Do not use it to keep treating unexplained vomiting. Suppressing the symptom while a cause goes unidentified is the real risk with any antiemetic.
Rehydrate. With vomiting, fluid and electrolyte loss matters more than the nausea itself — oral rehydration solution in small frequent sips is better than plain water.
Seek medical attention for vomiting that will not stop or prevents keeping fluids down; vomiting blood or material like coffee grounds; severe abdominal pain; a severe headache, stiff neck or visual disturbance with vomiting; confusion; signs of dehydration; eye pain with blurred vision or halos; inability to pass urine; or vomiting after a head injury. Seek urgent care for chest pain with nausea, which may be cardiac.
Related medicine guides
- Browse Digestive, Stomach & Nausea Medicines guides
- Read: Hyospasmol used for
- Read: Adco Contromet used for
Frequently asked questions
What is Medazine 50 mg used for? Preventing and treating nausea, vomiting and motion sickness, and relieving vertigo and inner-ear nausea. It contains cyclizine.
Is it the same as Valoid? The active ingredient is the same — cyclizine. The brand differs.
When should I take it for travel sickness? About an hour before travelling. It blocks the signal and cannot easily reverse nausea that is already established.
Will it make me drowsy? Commonly, yes. Do not drive until you know how it affects you, and avoid alcohol.
Why is it an antihistamine if I am not allergic? Histamine signalling drives the inner-ear and brainstem pathways that produce nausea. Blocking it there treats sickness, which is unrelated to allergy.
Can I take it for any kind of nausea? It works best for motion, vertigo and inner-ear causes. Nausea from gut problems or chemotherapy responds better to different medicines.