Along with its needed effects, vilanterol may cause some unwanted or undesirable effects.  

Although not all of these side effects may occur, if they do occur they may need medical attention. Check with your doctor immediately if any of the following side effects occur:

Less common:

• body aches or pain
• chest pain
• congestion
• cough
• dryness or soreness of the throat
• fever
• headache
• hoarseness or voice changes
• pain or tenderness around the eyes and cheekbones
• stuffy or runny nose
• tender, swollen glands in the neck
• tightness of the chest, trouble breathing
• trouble swallowing

Rare

• chest discomfort
• dizziness
• fainting
• fast or irregular heartbeat
• nausea or vomiting
• pain or discomfort in the arms, jaw, back, or neck
• sweating

Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

Less common

• diarrhea
• constipation
• muscle spasms

Rare

• burning, dry, or itching eyes
• dry mouth
• heartburn
• indigestion
• lack or loss of strength
• rash or itching skin
• redness, pain, swelling of the eye
• stomach upset

Other side effects not listed may also occur in some patients. If you notice any other effects, check with your doctor or pharmacist

Vilanterol trifenatate is a long-acting beta 2 agonist. It causes bronchodilation by relaxing the muscles in the breathing passages.

Do not use vilanterol in these cases:

• Known hypersensitivity to vilanterol or any ingredient in the formulation.

• Known severe hypersensitivity to milk proteins

Do not use for relief of acute symptoms.  Use a short-acting bronchodilator in these cases - they work more quickly.

Use vilanterol with caution:

• in patients with seizure disorders
• in patients with heart disorders
• in patients with overactive thyroid

Drug interactions:

• ketoconazole and other known strong CYP3A4 inhibitors (e.g., ritonavir, clarithromycin, conivaptan, indinavir, itraconazole, lopinavir, nefazodone, nelfinavir, saquinavir, telithromycin, troleandomycin, voriconazole). They may increase the blood levels of vilanterol
• MAOI medications (e.g., phenelzine)
• tricyclic antidepressants (e.g., amitriptyline, nortriptyline)
• Beta-blockers (e.g. propranolol, acebutolol)
• Diuretics or "water pills" (e.g. furosemide, hydrochlorothiazide)

Use in pregnancy: May interfere with uterine contractility. Carefully weigh benefit versus risk.  Consult with your doctor or pharmacist before use.

Use in breastfeeding: It is not known if vilanterol passes into breast milk.  Consult with your doctor or pharmacist before use.