a placebo-controlled crossover trial using cyproheptadine to treat children with functional abdominal pain

Conditions: Functional Abdominal Pain

Summary: the investigators hypothesize that using cyproheptadine in a placebo-controlled crossover trial would help relieve abdominal pain associated with (functional abdominal pain (fap) in children, achieving a greater response than that observed with placebo. in addition to assessing self-report of pain and other symptoms, the investigators also propose to perform experimental somatic pain testing to determine if there is evidence of peripherally-maintained central sensitization in children with fap. the investigators also hypothesize that there will be an increase in somatic pain threshold after completion of a cyproheptadine course compared to baseline testing prior to treatment, and compared to placebo. this would allow children with fap to return to normal function, improve symptoms and overall general well-being


Eligibility criteria:
inclusion criteria: * age between 8 and 18 years-old * diagnosed with functional abdominal pain using the rome iii criteria must include all\* of the following: 1. episodic or continuous abdominal pain 2. insufficient criteria for other fgids 3. no evidence of an inflammatory, anatomic, metabolic, or neoplastic process that explains the subject's symptoms * criteria fulfilled at least once per week for at least 2 months prior to diagnosis * written informed consent obtained from the patient/guardian before the initiation of any study-specific procedures exclusion criteria: * age \ 18 years-old * child or parent are non-english speakers * child is using other cns depressants (cyproheptadine causes drowsiness, and may enhance the adverse/toxic effect of other cns depressants e.g. opioids, barbiturates, droperidol, hydroxyzine, alcohol)(29) * child has a history of hypersensitivity to cyproheptadine products * child is currently using monoamine oxidase inhibitor (maoi e.g. nardil, marplan, parnate) (can cause a prolonged or intensified anticholinergic effect) * child was treated with cyproheptadine in the past 4 weeks * child is currently using anticholinergic (can cause an additive anticholinergic effect e.g. pramlintide) * concomitant ssri use ( being a serotonin antagonist, may oppose effects) * concomitant use of betahistine: antihistamines may diminish the therapeutic effect of betahistine * concomitant use of acetylcholinesterase inhibitors (central): anticholinergics may diminish the therapeutic effect of acetylcholinesterase inhibitors (central) and vice versa. * child has a personal history of glaucoma * child has asthma (can cause thickening of bronchial secretions) (27,28) * history of liver dysfunction/disease (can cause hepatitis) * history of cardiac disease (not specific to cyproheptadine, antihistamines have been associated with hypotension, palpitations, tachycardia and arrhythmias) (28,29). * females who are known to be pregnant will also be excluded. all females who are of child bearing age, or are already menstruating will perform a urine pregnancy test before enrolling. * any children who have difficulties swallowing tablets will receive teaching on how to swallow tablets. if they are still unable to do so, they will not participate in the study.