Mepolizumab (Subcutaneous)

If you are suffering from severe asthma and other medicines have failed to relieve your symptoms, then Mepolizumab may be prescribed.


Mepolizumab is given as an injection to patients suffering from severe asthma. It is usually given alongside other medicines as well. However, it is used when those other current asthma medicines are not working effectively.

Be aware that you can only obtain Mepolizumab with a prescription from your doctor. It has the potential to interact with other aspects of your health and drug or dietary intake so is not suitable for all patients. Instead, a different drug may be better suited. Either way, your doctor is best placed to decide whether this medicine is safe and suitable for you.

Condition(s) treated

  • Severe asthma

Type of medicine

  • Powder for solution

Side effects

As well as having its intended effects of treating severe asthma, it is possible that the Mepolizumab injection will cause you to experience some unwanted side effects. These side effects can range in their severity and their need for medical attention. Be aware that some patients may experience multiple side effects, whereas others may experience none at all. Below is a list of the more severe side effects that are possible. If you experience any of these after receiving the Mepolizumab injection, you should inform your nurse or doctor immediately.

Incidence not known

  • Confusion

As opposed to these more serious side effects, you may experience less serious ones which don't necessarily need medical assistance. In fact, you may find that such side effects will pass over time as your body adjusts to the new medicine. Directly below is a list of such medicines. However, you may still contact your doctor if you wish, especially if they are lingering or bothersome. They may be able to advise on some ways to help reduce the effects.

More common

Less common

  • Chills

Though these lists of side effects are extensive, they are not necessarily all-inclusive. This means you may experience some unwanted effects that have not been listed here. If this is the case and you are worried by them or would like to discuss them, you can still contact your nurse or doctor.


You will not need to worry about the exact doses of this medicine that you receive. It will be calculated by a trained doctor and you will receive the medicine from a trained health professional, such as a nurse or doctor. It is given as a shot underneath the skin. This will likely be in your stomach or abdomen, upper arm, or thigh. It is given once each 4 weeks to allow for ongoing relief from your symptoms.

Before being given the Mepolizumab injection you should be given a patient information leaflet. You should read this carefully and make sure you understand everything on it. If you do have any questions after reading this, then you should discuss these with your doctor.


It is possible that the Mepolizumab injection will interact with other drugs you are currently taking. As such, you will need to inform your doctor of any other drugs you are currently taking. This includes all prescription and nonprescription drugs. Your doctor can predict whether an interaction is likely to occur and then take the necessary steps to limit any unwanted interactions. For example, they may decide that they will need to change the Mepolizumab altogether or change the other interacting drug. In some cases, taking two drugs that are known to interact is actually best for your treatment. In such cases, your doctor may simply adjust the doses of either one or both of the interacting drugs.

As well as interacting with other drugs that you take, it is possible that Mepolizumab will interact with certain aspects of your typical dietary intake. Your doctor may advise you to make changes to how much or how frequently you smoke, eat, or drink certain things. You should follow any such guidance carefully as it will allow them to limit the chance of unwanted interactions occurring. For example, whilst you receive this injection, it may be necessary for you to drink less alcohol or smoke less tobacco.

Finally, other medical problems that you suffer from now, or in the past, may interact with the Mepolizumab injection. You should, therefore, give your doctor a full understanding of your medical history. They can then predict if any unwanted interactions will occur. In particular, the following medical problems are known to interact with this drug.

  • Parasitic infections. These infections should be properly treated before you start taking Mepolizumab


Before your doctor is able to prescribe you with Mepolizumab, they will first need to ensure they properly understand your medical health. This way they can decide if this drug is indeed the best course of treatment for you. As a part of this process, they will need to be made aware of any allergies you have. This includes allergies to animals, dyes, foods, or preservatives.

As of writing, no efficacy and safety have been established for the use of the Mepolizumab injection in children who are younger than 12 years old. This is because a lack of suitable studies have taken place into how the drug affects them.

The suitable studies that have so far taken place on elderly patients have not highlighted any geriatric-specific problems that would make the Mepolizumab injection any less useful in older patients. Do be aware though that older patients are more likely to suffer from age-related heart, liver, or kidney problems. If this is the case, then such patients will need to exercise greater levels of caution when receiving this drug. It may be that the dose given needs to be adjusted somehow.

As of writing, there are no suitable studies that have taken place on breastfeeding women receiving the Mepolizumab injection. It is unclear whether there are any increased risks either to the mother or the infant. Your doctor is best placed to inform you of any increased risks and together you can then weigh these against the benefits of using the medicine.

It is important that you visit your doctor at regular appointments if you are going to be receiving this medicine over a long period of time.You should attend all such scheduled appointments as your doctor is able to properly track your condition and ensure that this injection is suitable. They can check for any unwanted side effects and then make any necessary adjustments to your prescription.

After receiving this medicine, it is possible that some patients will experience a serious allergic reaction. If you have any of the following symptoms after receiving the Mepolizumab injection, contact your doctor immediately:

  • Large, hive-like swelling on face, legs, throat, hands, feet, sex organs, eyelids, lips, or tongue

Be aware that this medicine will not stop an asthma attack that is already underway. Instead, your doctor will need to prescribe an alternative medicine for this.

You may experience herpes zoster infection (shingles) after you receive this injection. To stop this, you might be given a vaccine before your treatment. If you have never had chickenpox or the chickenpox vaccine, then inform your doctor of this.

You should keep using your corticosteroid medicine to control your asthma up until your doctor tells you to stop using it.


You will not be required to store Mepolizumab at any time.


If you are suffering from severe asthma, then the Mepolizumab injection may be a helpful way to relieve your symptoms. Be aware that this injection will need to be given once every four weeks. This means that, if you are prescribed it, then you will need to attend regular appointments each month. Failing to do so could mean that your symptoms come back. These appointments are also vital for your doctor to check your condition and ensure the treatment is working properly.

Above, you can find details on the different side effects that may occur once you receive this drug. If you do experience any of the more severe ones, then you should contact your doctor immediately. Similarly, if you have any other questions about this drug or about your condition in general, then you should speak to your doctor.