Onset Injection Uses

About Onset Injection

Onset Injection uses include the prevention and treatment of nausea and vomiting caused by chemotherapy, radiotherapy, and surgery. It contains ondansetron, which blocks serotonin signals in the gut and brain that trigger the feeling of sickness and vomiting. Use it only under medical supervision because it is given by a doctor or nurse and the dose depends on the treatment, age, and body weight.

Onset Injection Uses

Your doctor might give you Onset Injection for:

• Nausea and vomiting caused by cancer chemotherapy
• Nausea and vomiting caused by radiotherapy
• Prevention of nausea and vomiting after surgery
• Treatment of nausea and vomiting after surgery

Onset Injection Dosage and Administration

Always follow your doctor's instructions exactly.

Adult Dosage:

• Each 4ml ampoule contains 8mg of ondansetron, and each 2ml ampoule contains 4mg
• Chemotherapy or radiotherapy: usually 8mg by slow injection into a vein or by drip just before treatment, then 8mg by mouth every 12 hours for up to 5 days
• Highly sickness-causing chemotherapy: the doctor may give up to 16mg as a drip over at least 15 minutes
• A single dose of more than 16mg must not be given
• Prevention of sickness after surgery: 4mg by slow injection into a vein or into a muscle at the start of anaesthesia
• Treatment of sickness after surgery: 4mg by injection into a muscle or slow injection into a vein
• Elderly 75 years and older: the first dose should not be more than 8mg, given as a drip over 15 minutes
• Moderate or severe liver disease: no more than 8mg in a day

Children Dosage:

• Chemotherapy, 6 months and older: 5mg per square metre of body surface or 0.15mg per kg into a vein just before treatment, up to 8mg per dose
• After chemotherapy, the doctor usually continues with ondansetron by mouth for up to 5 days
• The total dose in 24 hours must not be more than 32mg
• Sickness after surgery, 1 month and older: 0.1mg per kg by slow injection into a vein, up to 4mg

How to Take:

• It is given by a doctor or nurse in a hospital or clinic.
• It is injected slowly into a vein, given as a drip, or injected into a muscle.
• For chemotherapy, it is usually given just before the treatment starts.
• Your doctor may continue treatment with ondansetron tablets or syrup at home.
• Tell the nurse at once if you feel chest pain, a fast heartbeat, or swelling of the face during or after the injection.

Onset Injection Warnings

Don't use Onset Injection if you:

• Are allergic to ondansetron or any ingredient
• Are allergic to similar anti-sickness medicines such as granisetron
• Take apomorphine for Parkinson's disease

Onset Injection Precautions

Talk with your doctor first if you:

• Have a heart rhythm problem or a long QT interval
• Have heart failure or a slow heartbeat
• Have low potassium or magnesium in the blood
• Have liver disease
• Have signs of a blocked bowel or severe constipation
• Take medicines for depression such as SSRIs or SNRIs
• Take opioid painkillers such as buprenorphine or tramadol
• Take heart rhythm medicines, beta blockers, or other medicines that affect the heart rhythm
• Are pregnant, planning a pregnancy, or breastfeeding

Also, remember:

• It should not be used in the first 3 months of pregnancy
• Women who can become pregnant should consider using contraception
• Do not breastfeed while receiving it
• Tell your doctor at once about chest pain, as heart problems have been reported after injection
• After tonsil surgery, it can hide signs of bleeding, so you will be watched closely

Onset Injection Side Effects

Onset Injection is generally well tolerated, but some people may experience side effects.

• Headache
• Feeling warm or flushing
• Constipation
• Pain, redness, or swelling at the injection site

Serious side effects:

• Severe allergic reaction
• Irregular, fast, or slow heartbeat
• Chest pain
• Low blood pressure
• Seizures
• Uncontrolled body movements
• Temporary blurred vision or loss of sight
• Severe skin rash with blisters or peeling
• Agitation, sweating, shaking, or stiff muscles when taken with other serotonin medicines

Storage Instructions

• Store below 30°C
• Keep the ampoules in the original pack to protect from light
• Keep out of reach of children
• Do not use after expiry date

Packaging and Quantity

Onset Injection is available as:

• 4mg/2ml: Pack of 1 ampoule
• 8mg/4ml: Pack of 1 ampoule

Prescription Requirement

It is a prescription-only medicine due to its potential side effects and to prevent misuse.

Get Expert Advice on Marham Before Using Any Medicine

Marham enables you to communicate with experienced healthcare professionals to obtain professional guidance. Through Marham, you can find trusted doctors who provide expert advice about dosage and the effects of medicine. You can book an online and in-person appointment with specialist doctors at your nearby clinic through Marham's website, Android app, iOS app, and by calling 03111222398.

Frequently Asked Questions about Onset Injection

Disclaimer

The Marham platform strives to offer expert-reviewed information, which includes error elimination for all its consumers. Patients should always consult experts for medical advice instead of relying on this information. The information available on this page is for general information purposes only. Always seek medical advice from your doctor before using medicine or expressing health-related worries.