During a suspected asthma attack it is best not to give anything by mouth, except assisted ventilation in its worst stages. If this person is known to have a respiratory ailment and carries their own medication, follow the manufacturers instructions and assist the person to take it.
DO NOT delay in activating emergency services! Call 911 and tell the dispatcher that the person is having difficulty breathing. You can do something called SUPPORTIVE MEASURES. Be at their side, coach them in their breathing and ensure that they GET OXYGEN! If your workplace has an emergency oxygen unit get it on this person ASAP!
Loosen tight clothing around the chest and waist, make them comfortable, sit them straight up and slightly bent forward while supporting them, and most of all REASSURE them that help is on the way.