Functional Classes

After a right heart catheterization has been performed and PAH is diagnosed, the next step is determining the severity of the disease. The New York Heart Association (NYHA) created a scale called the NYHA Functional Classification system. It describes 4 categories based on symptoms associated with daily activities. The higher the functional class, the more PAH symptoms occur with less activity. This system helps doctors determine the severity of disease and appropriate type of treatment for their patients.

NYHA Functional Classes
Higher Functional Class = More symptoms with less activity
Class I No symptoms with ordinary activities
Class II Symptoms with ordinary activity; slight limitation of activity
Class III Symptoms with less than ordinary activity; marked limitation of activity
Class IV Symptoms with any activity, or even at rest


PAH is always progressing, and your physical symptoms may not always reflect what is happening inside your body. Different types of PAH treatment help compensate for 3 different substances in the body that become imbalanced in a person with PAH. Therefore, adding a second type of medication to your treatment regimen may make a difference. Keeping the lines of communication open with your healthcare team can help them make the best treatment decisions for you. Need help talking to your doctor? Download the Doctor Discussion Guide.

Next: Learn How PAH Is Treated


Before you take Tyvaso, tell your healthcare provider about all of your medical conditions, including if you:

It is important to tell your healthcare provider about all the medicines you may be taking, including prescription and non-prescription medicines, vitamins, and herbal supplements, as they may affect your use of Tyvaso by increasing the risk of side effects or decreasing effectiveness. Especially tell your healthcare provider if you take any of these medicines:

The most common side effects of Tyvaso are coughing, headache, throat irritation and pain, nausea, reddening of the face and neck (flushing), and fainting or loss of consciousness. These are not all the possible side effects of Tyvaso. Tell your healthcare provider about any side effects that bother you or do not go away. Your healthcare provider may be able to help you manage the side effects.


Tyvaso is a prescription medicine used in adults to treat pulmonary arterial hypertension (PAH) (WHO Group 1), which is high blood pressure in the arteries of your lungs. Tyvaso can improve exercise ability in people who also take bosentan (an endothelin receptor antagonist, (ERA)) or sildenafil (a phosphodiesterase-5 (PDE-5) inhibitor). Your ability to do exercise decreases 4 hours after taking Tyvaso.

The effects of Tyvaso are unknown in patients under 18 years of age.


Please see the Full Prescribing Information, Patient Package Insert, and the Tyvaso Inhalation System Instructions for Use manual.

For additional information about Tyvaso, visit or call 1-877-UNITHER (1-877-864- 8437).

Call your healthcare provider for medical advice about side effects. You may report side effects to the FDA at or call 1-800-FDA-1088.

This information is provided for an informational purpose and is not intended as treatment advice. Patients should consult a healthcare professional for treatment advice.