Acid reflux can cause painful heartburn which you can relieve with antacid medicines. That is, special medicines which neutralise the acid. Acid reflux happens mostly in people who are older and overweight. But it can happen in children and in all types of people.
In some studies, researchers have injected acid into the gullets of people with asthma, and it had a significant impact on their asthma and caused worse asthma symptoms.
These is also evidence to suggest that people who have asthma get acid reflux more often than people without asthma. This is probably because of the big pressure changes in the chest during breathing in people with asthma. These high pressures could force liquid to travel the wrong way up the oesophagus.
In these cases, asthma sufferers seem to lose out twice: they suffer from asthma and they may suffer from acid reflux more often than non asthma sufferers.
However, this is not the whole story. If acid reflux really was an important cause of asthma worsening, then treatments against acid reflux should make the asthma better, however, this is generally not the case.
In the meantime, if you have asthma and you also have acid reflux, it could just be that careful treatment of your reflux will make your breathing better.
If your asthma is bad and no-one knows why, some doctors would check whether you have or had acid reflux by conducting tests to measure the acidity in your gullet. If the result showed a tendency for acid reflux, then your doctor would probably try to improve your lungs by also treating your stomach.