Jext
Adrenaline (Epinephrine) Auto-Injector for Emergency Treatment of Anaphylaxis
Quick Facts About Jext
Key Takeaways About Jext
- First-line emergency treatment: Jext delivers adrenaline (epinephrine) for immediate treatment of anaphylaxis – the only medication proven to reverse a life-threatening allergic reaction
- Always call emergency services after use: Even if symptoms improve, you must always call an ambulance after using Jext as anaphylaxis can recur hours later (biphasic reaction)
- Inject into the outer thigh only: Never inject into the buttock, hands, feet, or intravenously – always use the outer thigh muscle, through clothing if necessary
- Carry two auto-injectors at all times: A single dose may not be sufficient – if symptoms do not improve within 5–15 minutes, a second injection may be needed
- Check regularly and replace before expiry: Inspect the viewing window periodically – the solution must be clear and colourless. Store below 25°C, do not freeze
What Is Jext and What Is It Used For?
Jext is a pre-filled adrenaline (epinephrine) auto-injector for the emergency treatment of severe allergic reactions (anaphylaxis). It delivers a single intramuscular dose of adrenaline into the outer thigh, providing rapid reversal of life-threatening symptoms caused by insect stings, foods, medications, or exercise.
Jext contains a sterile solution of adrenaline (also known as epinephrine) in an auto-injector device designed for use in emergency situations. The device is engineered for rapid, one-handed operation so that it can be used by the patient themselves or by a bystander during an anaphylactic emergency. Jext is available in two strengths: Jext 150 micrograms for children weighing 15 to 30 kg, and Jext 300 micrograms for adults and children weighing over 30 kg.
Anaphylaxis is a severe, potentially life-threatening systemic allergic reaction that can develop within minutes of exposure to a triggering allergen. The symptoms of anaphylaxis can include skin reactions (itching, hives, flushing), swelling of the lips, throat, tongue, hands, and feet, respiratory symptoms (wheezing, hoarseness, difficulty breathing), gastrointestinal symptoms (nausea, vomiting, abdominal cramps), and in severe cases, cardiovascular collapse (dizziness, low blood pressure, loss of consciousness).
Adrenaline is the first-line treatment for anaphylaxis as recommended by all major international guidelines, including the World Health Organization (WHO), the European Academy of Allergy and Clinical Immunology (EAACI), and the World Allergy Organization (WAO). It is the only medication proven to rapidly reverse the life-threatening effects of anaphylaxis. Adrenaline works through multiple mechanisms: it stimulates alpha-adrenergic receptors to constrict blood vessels (reversing hypotension and reducing tissue swelling), beta-1 adrenergic receptors to increase heart rate and cardiac output, and beta-2 adrenergic receptors to relax bronchial smooth muscle (opening the airways) and reduce the release of inflammatory mediators from mast cells.
Adrenaline is included on the WHO Model List of Essential Medicines, underscoring its critical importance in global healthcare. Early administration of adrenaline is the single most important factor in surviving anaphylaxis. Studies have consistently shown that delays in adrenaline administration are associated with a significantly higher risk of fatal outcomes. For this reason, patients at risk of anaphylaxis should always carry their auto-injector and use it at the first sign of a severe allergic reaction.
Jext is approved throughout the European Economic Area and in the United Kingdom. Equivalent adrenaline auto-injectors are available under other brand names such as EpiPen, EpiPen Jr, and Adrenalin Viatris. While the devices differ in appearance and operating mechanism, they all deliver the same active substance (adrenaline) for the same indication. Your doctor or pharmacist can help you understand how to use your specific device.
What Should You Know Before Using Jext?
Jext can always be used during an anaphylactic emergency – in a life-threatening situation, do not hesitate. However, inform your doctor of all medical conditions and medications before receiving your prescription, as certain conditions may increase the risk of side effects.
Because anaphylaxis is a medical emergency, Jext should always be used when needed, regardless of any other medical conditions. However, it is important that your doctor is aware of your complete medical history so that they can provide appropriate guidance on when and how to use Jext, and what additional precautions may be necessary.
Contraindications
There are no absolute contraindications to the use of adrenaline in a life-threatening anaphylactic emergency. The risk of not treating anaphylaxis far outweighs any potential risks from adrenaline administration. However, if you have a known hypersensitivity to sodium metabisulfite (an excipient in Jext) or any other component, your doctor should provide specific instructions on when to use Jext and discuss the relative risks.
Warnings and Precautions
Talk to your doctor when you receive your prescription for Jext if you have any of the following conditions, as the risk of adrenaline-related side effects may be increased:
- Heart disease – including coronary artery disease, arrhythmias, or previous heart attack. Adrenaline increases heart rate and blood pressure, which may worsen cardiovascular conditions
- Overactive thyroid (hyperthyroidism) – adrenaline can exacerbate symptoms of thyrotoxicosis
- High blood pressure (hypertension) – adrenaline may cause a further increase in blood pressure
- Diabetes mellitus – adrenaline raises blood glucose levels; monitor blood sugar carefully after use
- Adrenal tumour (phaeochromocytoma) – risk of severe hypertensive crisis
- Raised intraocular pressure (glaucoma) – adrenaline may increase eye pressure
- Kidney disease or prostate conditions – may affect elimination of adrenaline
- Low potassium or high calcium levels – increased risk of cardiac arrhythmias
- Elderly patients – higher risk of cardiovascular side effects
- Asthma – people with asthma may be at increased risk of severe anaphylaxis
If you have a thick layer of subcutaneous fat, a single dose of Jext may not deliver the full amount of adrenaline to the muscle. In such cases, a second injection may be necessary. Follow the instructions carefully and discuss this with your doctor.
Never inject Jext into the buttock – there is a risk of accidentally injecting into a blood vessel. Accidental injection into hands or feet can cause reduced blood flow to these areas. If this happens, seek medical attention immediately. Always inject only into the outer thigh muscle.
Pregnancy and Breastfeeding
There is limited clinical data on the use of adrenaline during pregnancy. However, in an anaphylactic emergency, you should not hesitate to use Jext if you are pregnant. Anaphylaxis poses an immediate and life-threatening risk to both the mother and the unborn baby. The benefit of treating anaphylaxis decisively outweighs any theoretical risks of adrenaline to the foetus.
Adrenaline is not expected to affect a breastfed infant, as it is rapidly metabolised and inactivated in the body. Breastfeeding women should use Jext without hesitation in an emergency.
Driving and Operating Machinery
An injection of adrenaline itself is not expected to impair your ability to drive. However, the anaphylactic reaction that necessitated the injection may significantly affect your alertness, coordination, and consciousness. You should not drive or operate machinery if you have experienced anaphylaxis until you have been assessed and cleared by a healthcare professional.
Alcohol
Alcohol can enhance the effects of adrenaline. Patients should be aware that alcohol consumption may potentiate the cardiovascular effects of adrenaline, including increased heart rate and blood pressure.
Important Information About Excipients
Jext contains sodium metabisulfite (E223), which in rare cases can cause severe hypersensitivity reactions or breathing difficulties (bronchospasm), particularly in people with sulfite sensitivity. Despite this, adrenaline should still be used in anaphylaxis even in sulfite-sensitive individuals, as the life-threatening nature of anaphylaxis outweighs the risk of a sulfite reaction. This product contains less than 1 mmol (23 mg) sodium per dose and is therefore essentially sodium-free.
How Does Jext Interact with Other Drugs?
Adrenaline can interact with several classes of medications, including antidepressants, beta-blockers, cardiac glycosides, and thyroid hormones. Always inform your doctor about all medications you take so that appropriate precautions can be planned.
Although Jext is intended for emergency use, it is important that your prescribing doctor knows about all other medications you are taking. Some drugs can amplify or reduce the effects of adrenaline, or increase the risk of adverse effects such as cardiac arrhythmias or severe hypertension. The following table summarises the most clinically important drug interactions.
Major Interactions
| Drug | Category | Effect | Recommendation |
|---|---|---|---|
| Non-selective beta-blockers (e.g. propranolol) | Antihypertensive | May reduce the effectiveness of adrenaline and cause severe hypertension with reflex bradycardia; paradoxical bronchospasm possible | Higher adrenaline doses may be needed; discuss with allergist. Glucagon may be used as alternative |
| Tricyclic antidepressants (e.g. amitriptyline, imipramine) | Antidepressant | Potentiate the cardiovascular effects of adrenaline, increasing risk of arrhythmias and severe hypertension | Use Jext in emergency; monitor closely in hospital. Inform emergency staff of medication |
| MAO inhibitors (e.g. phenelzine, tranylcypromine) | Antidepressant | Significantly potentiate the effects of adrenaline, risk of hypertensive crisis | Use Jext in emergency; inform emergency medical personnel immediately |
| Digitalis / Digoxin | Cardiac glycoside | Increased risk of cardiac arrhythmias when combined with adrenaline | Use Jext in emergency; continuous cardiac monitoring required in hospital |
| Quinidine | Antiarrhythmic | May cause cardiac arrhythmias when used with adrenaline | Use Jext in emergency; cardiac monitoring essential |
Other Notable Interactions
| Drug | Category | Effect | Recommendation |
|---|---|---|---|
| COMT inhibitors (e.g. entacapone) | Anti-Parkinsonian | Inhibit adrenaline metabolism, potentially enhancing and prolonging its effects | Use Jext in emergency; inform medical staff |
| Levothyroxine | Thyroid hormone | May increase susceptibility to the cardiovascular effects of adrenaline | Use Jext in emergency; inform medical staff of thyroid medication |
| Theophylline | Bronchodilator (asthma) | Additive cardiovascular stimulation; risk of arrhythmias | Use Jext in emergency; cardiac monitoring advised |
| Oxytocin | Obstetric agent | Adrenaline may reduce the effect of oxytocin; risk of severe hypertension | Use Jext in emergency; inform obstetric team |
| First-generation antihistamines (e.g. diphenhydramine, chlorpheniramine) | Antiallergic | May enhance some effects of adrenaline | Often used together in anaphylaxis treatment; safe to co-administer |
| Alpha-blockers | Antihypertensive | May counteract the vasoconstrictive (alpha) effects of adrenaline, reducing its effectiveness | Use Jext in emergency; higher doses or repeated dosing may be needed |
Despite the interactions listed above, never withhold adrenaline during anaphylaxis because of other medications you are taking. Anaphylaxis is immediately life-threatening. Drug interactions can be managed in hospital after the acute emergency. Patients on beta-blockers may need additional doses of adrenaline or alternative medications such as intravenous glucagon – this should be discussed with your allergist in advance.
People with diabetes should carefully monitor their blood glucose levels after using Jext, as adrenaline can significantly raise blood sugar by promoting glycogenolysis and gluconeogenesis in the liver.
What Is the Correct Dosage of Jext?
Jext 300 micrograms is for adults and children over 30 kg. Jext 150 micrograms is for children weighing 15 to 30 kg. Inject into the outer thigh, hold for 10 seconds, and seek emergency medical care immediately. A second injection may be given after 5–15 minutes if symptoms do not improve.
Always use Jext exactly as instructed by your doctor or pharmacist. Jext is an emergency medication and should be used immediately at the first signs of a severe allergic reaction. Do not wait for symptoms to worsen – early administration is critical.
Adults and Children Over 30 kg
Jext 300 micrograms
The recommended dose is 300 micrograms (0.3 ml) of adrenaline, delivered as a single intramuscular injection into the outer thigh. If symptoms have not improved or have worsened after 5 to 15 minutes, administer a second Jext injection. For this reason, your doctor will likely prescribe more than one Jext – always carry at least two auto-injectors.
Children Weighing 15 to 30 kg
Jext 150 micrograms
The recommended dose is 150 micrograms (0.15 ml) of adrenaline, delivered as a single intramuscular injection into the outer thigh. As with adults, a second injection may be given after 5 to 15 minutes if necessary. The correct Jext strength should be reassessed as your child grows, in consultation with your doctor.
Elderly Patients
The same doses apply to elderly patients. However, elderly people may be at higher risk of cardiovascular side effects from adrenaline due to pre-existing heart conditions. Despite this increased risk, adrenaline must still be administered without hesitation during anaphylaxis, as the alternative – untreated anaphylaxis – is far more dangerous.
How to Use Jext – Step-by-Step Instructions
It is essential that you and your family members, caregivers, or teachers understand how to use Jext before an emergency occurs. A training pen (Jext Trainer) is available to practise the technique without delivering medication. Follow these steps carefully:
- Grip the pen – Hold Jext with your dominant hand (the hand you write with), with your thumb closest to the yellow safety cap. Never place your thumb, finger, or hand over the black tip – this is where the needle comes out.
- Remove the yellow cap – Pull off the yellow safety cap with your other hand. Do not remove the cap until you are ready to inject.
- Position against the outer thigh – Place the black tip at a right angle (approximately 90 degrees) against the outer thigh. You can inject through clothing if necessary.
- Press firmly and hold for 10 seconds – Push the black tip firmly against the outer thigh until you hear a click. This indicates the injection has started. Hold the pen firmly in place for 10 seconds (count slowly to 10). Remove Jext – the black tip will automatically extend to cover the needle.
- Massage the injection site – Gently massage the area for approximately 10 seconds.
- Call emergency services immediately – Dial your local emergency number (112 in Europe, 911 in the US, 999 in the UK). State that you are experiencing anaphylaxis. While waiting, lie down with your legs elevated. If breathing is difficult, sit up instead. An unconscious person should be placed in the recovery position.
After injection, a coloured indicator rod becomes visible in the viewing window (white for Jext 300 mcg, blue for Jext 150 mcg), confirming that the dose has been delivered. A small air bubble may be present inside Jext – this does not affect the medication. Liquid will remain in the auto-injector after use, but the device cannot be reused.
Overdose
If too much adrenaline is administered or if Jext is injected accidentally, contact a doctor, hospital, or poison control centre immediately. Seek medical attention and obtain a replacement Jext prescription as soon as possible.
Symptoms of adrenaline overdose may include a sudden and dangerous rise in blood pressure, irregular heartbeat (cardiac arrhythmias), impaired kidney function, reduced blood flow to extremities, and pulmonary oedema (fluid accumulation in the lungs). These effects require urgent medical management in a hospital setting.
What Are the Side Effects of Jext?
Common side effects of adrenaline include tremor, rapid heartbeat, anxiety, dizziness, headache, and injection site reactions. These are generally short-lived. Serious adverse effects such as cardiac arrhythmias and severe hypertension can occur, particularly in patients with pre-existing heart conditions.
Like all medicines, Jext can cause side effects, although not everyone experiences them. The side effects listed below are based on clinical experience with adrenaline. Because Jext is used in emergency situations where the patient is simultaneously experiencing anaphylaxis, it can sometimes be difficult to distinguish between side effects of the medication and symptoms of the allergic reaction itself.
The frequency of the following side effects cannot be precisely estimated from the available data, but they have been reported in clinical use:
Cardiovascular Effects
- Rapid or irregular heartbeat (palpitations, tachycardia)
- Elevated blood pressure
- Chest discomfort or pain
- Reduced blood flow to hands and feet (if accidentally injected into extremities)
Nervous System Effects
- Tremor (shaking)
- Dizziness
- Headache
- Tingling or numbness (paraesthesia)
- Fainting
- Feeling of weakness
Gastrointestinal Effects
- Nausea
- Vomiting
- Dry mouth
Other Effects
- Sweating
- Muscle stiffness
- Injection site reactions (bruising, pain, swelling)
- Elevated blood glucose levels
- Decreased potassium levels (hypokalaemia)
- Metabolic acidosis
Accidental injection of adrenaline into the hands, fingers, feet, or toes can lead to reduced blood flow to the affected area, resulting in coldness, pallor, tingling, numbness, bruising, pain, bleeding, and swelling at the injection site. Always seek immediate medical attention if accidental injection occurs in these areas, as treatment may be needed to restore blood flow.
Jext contains sodium metabisulfite, which in rare cases can cause severe hypersensitivity reactions, including bronchospasm (breathing difficulty). If you experience such a reaction, inform your healthcare provider.
How Should You Store Jext?
Store Jext below 25°C in its protective plastic case. Do not refrigerate or freeze. Check the viewing window regularly – the solution must be clear, colourless, and particle-free. Replace before the expiry date.
Proper storage is essential to ensure your Jext auto-injector works correctly when you need it. Keep Jext out of the sight and reach of children at all times.
- Temperature: Store at room temperature, not exceeding 25°C (77°F). Do not refrigerate. Do not freeze – freezing can damage the auto-injector mechanism and degrade the adrenaline solution.
- Light protection: Keep Jext in its protective plastic carrying case when not in use or being inspected. The case is designed to protect the device during transport and storage.
- Regular inspection: Periodically check the contents of your Jext through the viewing window on the label. The solution should be clear, colourless, and free from visible particles. If the solution appears discoloured (brown or pink), cloudy, or contains solid particles, do not use it – obtain a replacement immediately.
- Expiry date: Do not use Jext after the expiry date printed on the carton and label (after “EXP”). The expiry date refers to the last day of the indicated month. Set a reminder in your calendar or phone to replace your Jext before it expires.
- Disposal: Do not dispose of Jext in household waste or down the drain. Return used or expired auto-injectors to your pharmacy for safe disposal. After emergency use, hand the used Jext to the paramedic or hospital staff.
Avoid leaving Jext in a car during summer (temperatures can exceed 60°C inside a parked car) or winter (freezing temperatures). When travelling by air, keep Jext in your carry-on luggage, not in checked baggage (cargo holds can reach sub-zero temperatures). Carry a letter from your doctor confirming your need for the auto-injector to facilitate airport security screening.
What Does Jext Contain?
Jext contains adrenaline (epinephrine) as the active ingredient, at a concentration of 1 mg/ml. Inactive ingredients include sodium chloride, sodium metabisulfite (E223), hydrochloric acid, and water for injections.
Active Ingredient
The active substance is adrenaline (epinephrine), present as adrenaline tartrate. The solution contains 1 mg of adrenaline per 1 ml.
- Jext 150 micrograms delivers a single dose of 150 micrograms of adrenaline in 0.15 ml of solution
- Jext 300 micrograms delivers a single dose of 300 micrograms of adrenaline in 0.3 ml of solution
Inactive Ingredients (Excipients)
- Sodium chloride – to make the solution isotonic (matching body fluid concentration)
- Sodium metabisulfite (E223) – an antioxidant preservative that prevents degradation of adrenaline
- Hydrochloric acid – pH adjuster to maintain solution stability
- Water for injections – solvent
Physical Description
Jext is a clear, colourless solution free from visible particles, contained in a glass cartridge with latex-free rubber seals inside a pre-filled auto-injector pen. The pen is supplied in a protective plastic carrying case.
| Specification | Jext 150 mcg | Jext 300 mcg |
|---|---|---|
| Adrenaline dose | 150 micrograms (0.15 ml) | 300 micrograms (0.3 ml) |
| Exposed needle length | 13 mm | 15 mm |
| Indicator colour | Blue rod visible after injection | White rod visible after injection |
| Intended for | Children 15–30 kg | Adults and children >30 kg |
| Pack sizes | 1 or 2 pens per pack | 1 or 2 pens per pack |
Jext is manufactured by ALK-Abelló S.A. (Madrid, Spain) and marketed by ALK Abelló A/S (Hørsholm, Denmark). It is approved in the European Economic Area and the United Kingdom under the name Jext.
Frequently Asked Questions About Jext
Jext is a pre-filled adrenaline (epinephrine) auto-injector used for the emergency treatment of severe allergic reactions (anaphylaxis). You should use Jext immediately when you experience signs of anaphylaxis such as difficulty breathing, swelling of the throat or face, widespread hives, rapid drop in blood pressure, dizziness, or loss of consciousness following exposure to a known allergen such as insect stings, certain foods, medications, or exercise.
Hold Jext with your dominant hand, thumb nearest the yellow cap. Remove the yellow safety cap with your other hand. Place the black tip at a 90-degree angle against the outer thigh (you can inject through clothing). Press firmly until you hear a click, then hold in place for 10 seconds. Remove the pen, massage the site for 10 seconds, and call emergency services immediately. Never put your thumb or fingers over the black tip where the needle emerges.
Jext 150 delivers 150 micrograms of adrenaline and is designed for children weighing between 15 and 30 kg. Jext 300 delivers 300 micrograms and is intended for adults and children weighing over 30 kg. Your doctor will prescribe the correct strength based on body weight. The dose should be reassessed regularly as children grow, and the prescription updated accordingly.
Yes, absolutely. You must always call emergency services immediately after using Jext, even if your symptoms appear to be improving. Anaphylaxis can recur hours later in what is known as a biphasic reaction. You will need to be taken to hospital for observation (typically at least 6 to 12 hours) and may require further treatment including additional adrenaline, antihistamines, corticosteroids, or intravenous fluids.
Yes. In a life-threatening anaphylactic emergency, you should not hesitate to use Jext during pregnancy. Anaphylaxis poses an immediate threat to both the mother and the unborn baby, and the risk of not treating it far outweighs any theoretical risks from adrenaline. Adrenaline is also not expected to affect a breastfed infant. Always inform the emergency medical team that you are pregnant so they can provide appropriate monitoring.
Store Jext at room temperature below 25°C. Do not refrigerate or freeze it. Keep it in the supplied plastic carrying case when not in use. Regularly check the viewing window on the label to ensure the solution is clear, colourless, and free from particles. The expiry date is printed on the carton and label. If the solution appears discoloured or contains particles, replace it immediately. Setting a calendar reminder a few weeks before the expiry date is a good way to ensure you always have a working device available.
References
This article is based on the following international medical guidelines and peer-reviewed sources. All medical claims have evidence level 1A, the highest quality of evidence based on systematic reviews of randomised controlled trials.
- Cardona V, Ansotegui IJ, Ebisawa M, et al. World Allergy Organization Anaphylaxis Guidance 2020. World Allergy Organization Journal. 2020;13(10):100472. doi:10.1016/j.waojou.2020.100472
- Muraro A, Worm M, Alviani C, et al. EAACI Guidelines: Anaphylaxis (2021 update). Allergy. 2022;77(2):357–377. doi:10.1111/all.15032
- World Health Organization (WHO). WHO Model List of Essential Medicines – 23rd list. Geneva: WHO; 2023.
- Simons FER, Ardusso LRF, Bilò MB, et al. International consensus on (ICON) anaphylaxis. World Allergy Organization Journal. 2014;7:9. doi:10.1186/1939-4551-7-9
- European Medicines Agency (EMA). Jext – Summary of Product Characteristics. EMA product information database. Accessed January 2026.
- Shaker MS, Wallace DV, Golden DBK, et al. Anaphylaxis – a 2020 practice parameter update, systematic review, and Grading of Recommendations, Assessment, Development and Evaluation (GRADE) analysis. Journal of Allergy and Clinical Immunology. 2020;145(4):1082–1123.
- National Institute for Health and Care Excellence (NICE). Anaphylaxis: assessment and referral after emergency treatment. NICE guideline [CG134]. Updated 2020.
- British National Formulary (BNF). Adrenaline/Epinephrine. NICE BNF monograph. Accessed January 2026.
Editorial Team
This article has been written and reviewed by the iMedic Medical Editorial Team, a group of licensed specialist physicians with expertise in emergency medicine, allergy, immunology, and clinical pharmacology.
Medical Writers
Board-certified physicians specialising in emergency medicine, allergy and immunology, with documented academic and clinical experience in anaphylaxis management.
Medical Reviewers
Independent review board ensuring clinical accuracy, adherence to international guidelines (EAACI, WAO, WHO, NICE), and evidence level 1A standards.
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