Cyclizine

What is Cyclizine?

Cyclizine is an anti-sickness tablet which contains an antihistamine called cyclizine hydrochloride.

Cyclizine was developed by an American pharmaceutical company - which is now GlaxoSmithKline (GSK) - during a study of antihistamines. The study revealed Cyclizine to be a long-acting and effective anti-sickness treatment. NASA famously chose Cyclizine for the Apollo 11 space mission to the moon due to its anti-emetic properties.

As an anti-nausea treatment, Cyclizine is well tolerated and is used to reduce sickness brought on from other medications, such as opioids and anaesthetics, as well as motion sickness and labyrinthine disorders.

"Nausea, or the feeling of sickness, is often attributed to vertigo. But it can also be brought on as a side effect of medicines or from sporadic movement when travelling in a car or boat. If a person experiences sickness often, Cyclizine can be prescribed to help them manage their condition and prevent the sensation from worsening." Mohamed Imran Lakhi, Superintendent Pharmacist

Cyclizine is a generic medicine which is available over the counter from pharmacies in the UK. Though, your doctor may prescribe cyclizine for certain conditions.

What is Cyclizine used for?

Cyclizine is used to treat:

• Nausea (feeling sick)
• Vomiting (being sick)
• Motion sickness
• Vertigo
• Labyrinthine disorders (such as labyrinthitis)

Cyclizine may be used to treat nausea brought on from other medications, such as anaesthetics.

While it is not advised by manufacturers to take Cyclizine during pregnancy, Cyclizine may be used to treat severe morning sickness (hyperemesis gravidarum).

If you are feeling sick, speak to your doctor or pharmacist before you buy Cyclizine anti-sickness tablets to ensure they are safe for you to take.

What is motion sickness?

Motion sickness is a feeling of nausea and malaise which is often caused by a moving vehicle.

The vestibular apparatus in the inner ear relays information to the brain about the position of the body. This apparatus gives us our sense of balance and orientation.

Together, the eyes, inner ear and brain determine whether the body is in motion. They send messages to one another, asking whether there is motion which can be both felt and seen.

What causes motion sickness?

Motion sickness occurs when these messages do not match. The sensation can come about from the following situations:

The vestibular apparatus senses motion when no motion is perceived. This happens in aircraft and boats with limited ways of viewing the horizon or movement of the vehicle. It can also occur in a car if you look at something like a book or electronic device while the car is in motion.

Motion is perceived but not reported by the vestibular apparatus. This is also referred to as simulator sickness and has been countlessly reported during the screenings of films with erratic movements.

During these situations, the brain becomes confused and releases chemicals called histamines to induce vomiting.

How does Cyclizine work?

Cyclizine blocks histamine and muscarinic receptors located in the chemoreceptor trigger zone (CTZ) in the brain.

The CTZ is found in the medulla oblongata of the brain. The medulla oblongata is responsible for involuntary responses such as sneezing and vomiting.

Cyclizine binds to receptors in the brain and prevents histamine, an emetic (nausea causing substance), from binding.

By blocking the histamine from reaching and binding to the receptor, the emetic effect is reduced and the feeling of sickness subsides.

How to take Cyclizine?

Cyclizine should be taken as recommended by the doctor.

To prevent motion sickness, take one 50 mg tablet with a glass of water an hour or two before travelling.

Cyclizine can be taken with or without food.

Cyclizine side effects and cautions

All medicines carry the risk of side effects. It's important to understand and be able to identify the possible side effects associated with your medicine.

Before you take Cyclizine anti-sickness tablets, familiarise yourself with the information found in the leaflet enclosed with your medication. The leaflet contains important information on how to take and store cyclizine, as well as a complete list of side effects and risks. Always retain the leaflet in case you need to read it again.

Who shouldn't take Cyclizine?

Cyclizine should be used with caution in people with:

• Epilepsy
• Glaucoma
• Liver disease
• Men with an enlarged prostate gland (prostatic hypertrophy)
• Obstruction in the stomach or intestines
• Severe heart failure

Will Cyclizine interact with any other medication I am taking?

Tell your doctor if you are taking any other prescribed, over-the-counter or herbal medicines.

Side effects of Cyclizine may include:

• Blurred vision
• Constipation
• Convulsions
• Dizziness
• Drowsiness
• Dry mouth, nose or throat
• Hallucinations
• Headaches
• Increased blood pressure
• Insomnia
• Jaundice (yellowing of the skin and whites of the eyes)
• Nervousness
• Rash
• Restlessness
• Tachycardia (increased heart rate)
• Tingling in the extremities
• Tremor
• Urinary retention (difficulty urinating)

The above is not an exhaustive list of side effects. A more detailed list of side effects can be found in the patient information leaflet enclosed with your medicine. You can also visit  NHS UK for further information.

If you experience any side effects, report them to your doctor.

Do not take Cyclizine if you are allergic to any of the following ingredients:

• Acacia
• Lactose
• Magnesium stearate
• Potato starch

Allergies

Signs of an allergic reaction include:

• Chest tightening
• Dry, red and cracked skin
• Itchy, red watery eyes
• Raised, itchy, red rash (hives)
• Swelling of the lips, tongue, eyes or face
• Tummy pain, nausea, vomiting or diarrhoea
• Wheezing

Other safety information

Do not take Cyclizine past the expiry date printed on the packaging. The date refers to the last day of the specified month.

Never throw away medicine via household or water waste. Take any unwanted or expired medication to your local pharmacy and ask them to dispose of it safely on your behalf. You can find your nearest pharmacy using the NHS' Find a Pharmacy service.

Always store your medicine out of sight and reach from children and pets.

Never share your medicine with anybody else. Even if they are experiencing the same symptoms or have been diagnosed with the same condition as you.

Frequently asked questions

Sources

https://www.nhs.uk/medicines/cyclizine/

Brown and Burk UK Limited. Cyclizine Hydrochloride 50mg Tablets: Summary of Product Characteristics.

Additional resources

3 ways to treat nausea at home