Asthma is a common inflammatory airway disease. Several researches have demonstrated a possible connection between asthma and exposure to paracetamol.

Our hypothesis is that even a single dose of paracetamol is sufficient to cause a measurable change in lung functions.

This trial aims to identify a possible effect of single dose paracetamol on lower airway function.

Asthma is a common inflammatory airway disease and its prevalence is on the rise all around the world, Most significantly in children under 5 years.

Paracetamol is one of the most common drugs used with children at thus age groups and several studies have proved a causative connection between exposure to paracetamol and asthma prevalence as well as other allergic conditions.

The mechanism is presumably by reduction of glutathione level, resulting in oxidative burst and formation of reactive oxygen species (ROS).

In addition, paracetamol maybe directly cytotoxic to pneumocytes if given in overdose.

The goal of this research is to identify and quantify the effect of single dose of paracetamol on lung functions of asthmatic and healthy subjects.

The study group will include 40 children aged 7-16 years, who are known to have asthma and a control group of 20 healthy children.

The children will be randomized to receive a dose of paracetamol or placebo, and lung functions will be measured by both spirometry and Fraction of expired Nitric Oxide (FeNO) test.

Each child will receive both paracetamol and placebo, randomly in to consecutive tests, thus children will serve as their own control.

Inclusion Criteria:

• age: 7-16 years
• research group: children who have been diagnosed as asthmatic according to the American thoracic society (ATS) criteria
• control group: children who are not known to have asthma

Exclusion Criteria:

• paracetamol sensitivity
• children with any kind of chronic disease (except asthma)
• children with non asthma related chronic lung disease
• acute asthma attack
• children on systemic steroids