Do not drive or use machinery for 5 hours after taking melatonin.Do not use if you are pregnant or breastfeeding. Consumption with alcohol, or other medications or natural health products with sedative properties is not recommended. If symptoms persist for more than 4 weeks (chronic insomnia), consult your health care practitioner. Consult a health care practitioner prior to use if you are taking any of the following medications: anticoagulant, anticonvulsant, blood pressure medications, immunosuppressive medications, sedative, hypnotic or psychotropic medications, or steroids. Consult a health care practitioner prior to use if you have asthma, cardiovasculardisease, chronic kidney disease, depression, diabetes or hypoglycaemia, hormonal disorder, immune system disease, liver disease, migraine, or seizure disorders. Mild gastrointestinal symptoms (nausea, vomiting, or cramping) and rare allergic reactions have been known to occur; in which case, discontinue use.