My daughter is 2 months shy of her 8th birthday. She has always been a very tiny girl compared to her entire class. She has had chronic asthma since she was an infant. Honestly, I thought we would not see her 4th birthday due to her asthma. Singulair causes many of these reported side effects as Hailey has experienced many.
However, due to the fact that she can't breath without it I tried to self medicate her by lowering her dose. Since she is smaller than most we tried cutting the 4mg tablets in half and started her off at one half every other day in the morning with breakfast. Then as she got used to it slowly ....we started to increase her dose. Now at almost 8 years old she weighs 45 lbs. and is 3 foot 8 inches tall, still the shortest in her second grade class. We now give her 1/2 of a 5mg chewable every morning and she does great with little to no side effects and the best part is her asthma is manageable. Hailey does complain sometimes of side effects (headaches, stomach aches, arms tingling) but without the Singulair she needs her treatments 2 times per day along with her inhaler and suffers to just make it through the day.
She still needs treatments if she is exposed to allergens like cats, dogs, outdoor pollens, to many milk products in one day, etc. Sometimes I take her off the Singulair for a day or two just to give her body a break. I sympathize with many parents but never got my asthma doctor to bring up the idea to lower her dose. My regular pediatrician said it couldn't hurt when I suggested we lower her dose, and it worked for our daughter!