Could I take singular for asthma and take Claritin (loratadine) and lohist-d for allergy at the same time?

Yes. Singulair (montelukast) and Claritin work by different mechanisms. The combination of both works better than either alone for allergy control and the singulair (montelukast) may help your asthma as well.
Not sure about... ...The d ("decongestant") in lohist-d. It is useless in some people, and raises blood pressure in some others.

Related Questions

How effective is Claritin (loratadine) d to help with allergy asthma?

Antihistamines help. Claritin (loratadine) +/- d, zyrtec +/- d, or Allegra +/- d can help with allergy and asthma symptoms caused by allergies to respiratory pollens or other airborne allergens. One should work with his doctor to see which combination of over-the-counter allergy meds and prescription asthma inhalers/pills work the best. A patient will learn over time, what medicines to adjust, depending on how "bad" the air is. Read more...
Some. Post nasal drip is a great irritant to asthmatics with allergies. Getting your allergies treated and clearing the mucus from the upper airway works quite well - nasal rinses + nasal steroids. If these don't work for you completely adding Claritin usually helps somewhat. Read more...

My sister age 16 has insomnia for the first time what should she do to cure it? She doesn't wheeze. She takes an inhaler for asthma and loratadine.

Many reasons. There are many reasons for insomnia. If she is taking Loratadine d, the "d" part can keep people awake. Occasionally antihistamines will also keep people awake. Some asthma inhalers can also keep people awake especially if they are used too often. Call the doctor who prescribed the inhaler for advice. Read more...