What to Know About Cinqair (Reslizumab)

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Cinqair (reslizumab) is an injectable biologic drug used to treat a rare but severe form of asthma known as eosinophilic asthma. It is delivered intravenously (into a vein) every four weeks to control asthma symptoms, typically only after asthma inhalers and oral medications fail to provide relief. The most common side effect is mouth and throat pain.

There are no generic versions of Cinqair.

Nurse setting up IV drip
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Cinqair is approved by the Food and Drug Administration (FDA) for use as a controller medication for adults 18 and over with severe eosinophilic asthma. It is prescribed as an add-on therapy in conjunction with other chronic asthma medications. Cinqair is never used on its own.

With eosinophilic asthma, the immune system overreacts and produces excessive amounts of eosinophils in the airways. These are white blood cells deployed by the immune system to fight disease.

This not only increases inflammation and the frequency and severity of asthma attacks, but it can also damage tissues and lead to the formation of nasal polyps.

Cinqair works by blocking the process by which eosinophils are produced to stunt this immune response.

When injected into a vein, Cinquir binds to interleukin-5 (IL-5). IL-5 is a signaling protein secreted by the immune system that instigates the release of eosinophils from bone marrow. The binding blocks the action of IL-5 and effectively reduces eosinophil levels in the airways.

Cinqair is not used to treat acute attacks but rather to sustain control of asthma symptoms by reducing eosinophilic inflammation in the airways.

Cinqair is a biologic classified as a humanized monoclonal antibody. Humanized monoclonal antibodies are antibodies derived from animals, often mice, that are modified to match those in humans.

Other monoclonal antibodies used to treat eosinophilic asthma include Dupixent (dupilumab), Fasenra (benralizumab), Nucala (mepolizumab), and Xolair (omalizumab). Each reduces airway inflammation in slightly different ways.

Off-Label Uses

Cinqair is not approved to treat any eosinophilic condition aside from eosinophilic asthma.

With that said, a growing number of scientists and healthcare providers have begun to endorse the use of Cinqair in people with severe eosinophilic esophagitis, an inflammatory condition commonly associated with food allergies. Studies have even shown the drug to be safe for children over 9.

Before Taking

Your healthcare provider will want to confirm that your asthma is associated with eosinophilia (high eosinophil count) before prescribing Cinqair.

To do this, they will conduct a sputum test in which you cough up sputum (saliva and mucus) that is then examined in a lab. Eosinophilia can be diagnosed when eosinophils account for more than 3.5% of the total white blood cells in a sputum sample.

While blood tests are also useful in diagnosing eosinophilia, a high eosinophil count in the blood doesn't always translate to a high eosinophil count in the airways. If needed, a bronchial biopsy (involving the extraction of tissue from the large airways) can provide definitive evidence.

All of this said, having asthma and eosinophilia doesn't necessarily mean Cinqair is the right drug choice for you. It is typically only used when you have severe persistent asthma with eosinophilia, as opposed to mild to moderate persistent asthma.

Severe persistent asthma is broadly defined as:

  • Needing to use a rescue inhaler several times daily
  • Needing oral corticosteroid drugs two or more times per year to treat severe asthma attacks
  • Having nighttime attacks several times weekly
  • Having reduced lung function (defined as an FEV1 of less than 60% of your expected value or a reduction of your FEV1/FVC ratio by more than 5%)

To assess these factors, the healthcare provider will use an evaluative questionnaire, such as the Asthma Control Questionnaire (ACQ) issued by the Global Initiative for Asthma (GINA). The ACQ scores asthma based on the frequency and severity of attacks, the frequency of medication use, and the degree to which the attacks affect your ability to function normally. Also included in the ACQ assessment are pulmonary function tests (PFTs) to measure your FEV1 and FVC values.

To aid in the diagnosis, you should keep a diary detailing when attacks occurred in the past week and how many times you used your rescue inhaler.

Cinqair is typically prescribed when controller medications like inhaled corticosteroids, inhaled long-acting bronchodilators, and oral leukotriene modifiers fail to relieve severe eosinophilic asthma symptoms.

Precautions and Contraindications

The only absolute contraindication for Cinqair use is a known allergy to reslizumab or any of the other ingredients in the drug.

Cinqair treatment should be delayed if you have a parasitic worm infection like tapeworms. Eosinophils are essential to the control of parasites and suppressing them can make a parasitic infection worse. If you have a parasitic infection, it is important to get it treated and cured before starting Cinqair.

There is circumstantial evidence that Cinqair may increase the risk of certain cancers. According to premarket research, 0.6% of users were diagnosed with cancer within six months of starting Cinqair compared to 0.3% of users given a placebo.

There was no clear association between the types of cancer involved. Even so, it is important to advise your healthcare provider if you have a family history of cancer, have had cancer, or are undergoing treatment for cancer prior to starting Cinqair.

The safety of Cinqair in pregnancy is unknown, although animal studies have not shown evidence of fetal harm. It is also unknown if reslizumab can be passed through breastmilk and what harm that may pose to nursing babies.

If you are pregnant, breastfeeding, or planning to get pregnant, speak with your healthcare provider to fully understand the possible benefits and risks of Cinqair use.


Cinqair is given by an intravenous (IV) infusion in a healthcare provider's office or infusion center every four weeks.

The recommended dose of Cinqair is calculated as 3 milligrams per kilograms (mg/kg) of body weight. If you weighed 120 pounds (54 kg), for example, your recommended dose would be 162 mg (54 x 3 mg = 162 mg).

The recommended dose is then mixed with 50 milliliters (ml) of saline solution and delivered into a vein using a needle and IV drip. Each treatment is delivered over 20 to 50 minutes.

Cinqair is neither self-administered nor stored at home. It must be given by a medical professional in a healthcare setting in the event of an allergic reaction.

If you are just starting treatment, you may be asked to stay for 20 to 30 minutes after the infusion to ensure that you have no allergic reaction to the drug. You will also be advised of the symptoms of a drug allergy and given instructions on who to call and what to do if any symptoms develop.

Possible Side Effects

As with all medications, Cinqair may cause side effects. Most are mild and resolve as your body adapts to the drug.


The most common side effects of Cinqair (affecting at least 1% of users) include:

  • Injection site pain, redness, or redness
  • Throat and mouth pain
  • Muscle pain (particularly the neck, chest, arms, and legs)
  • Muscle spasms
  • Weakness


On rare occasions, Cinqair can cause a potentially life-threatening, whole-body allergy called anaphylaxis. Anaphylaxis symptoms tend to occur within 20 minutes of an infusion and as early as the second dose of treatment.

Anaphylaxis is a medical emergency. If left untreated, anaphylaxis can lead to shock, coma, asphyxiation, heart or lung failure, and death.

When to Call 911

Seek emergency care if you experience some or all of the following after a Cinqair infusion:

  • Hives or rash
  • Shortness of breath
  • Wheezing
  • Dizziness or lightheadedness
  • Rapid or irregular heartbeat
  • Nausea or vomiting
  • Confusion
  • Swelling of the face, tongue, or throat
  • A feeling of impending doom

Warnings and Interactions

The FDA has issued a black box warning advising consumers and health professionals of the risk of anaphylaxis with Cinqair. According to premarket research, 0.3% of users experienced anaphylaxis symptoms, most typically vomiting, wheezing, and hives.

A black box warning is the highest level of alert issued by the FDA to protect consumers from serious safety risks.

Because Cinqair is recognized by the immune system as a naturally occurring antibody, it neither appears to alter the metabolism of drugs nor cause drug interactions of any sort. Even so, advise your healthcare provider about any and all drugs you are taking before starting Cinqair.

9 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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By Daniel More, MD
Daniel More, MD, is a board-certified allergist and clinical immunologist. He is an assistant clinical professor at the University of California, San Francisco School of Medicine and currently practices at Central Coast Allergy and Asthma in Salinas, California.