The effects of your morning cup of coffee depend on what else you have with it. Those who drink caffeine are more likely to smoke cigarettes, which is understandable as surveys show that caffeine makes cigarettes more desirable. However, there is evidence that combining the two can have severe side effects. If you smoke a cigarette after drinking coffee, the caffeine intensifies the effects of nicotine and can make you much more likely to have a heart attack than either would alone. This is likely because caffeine and nicotine together make your heart stiffer, which is something doctors look for when diagnosing cardiovascular disease. A stiffer heart is associated with serious health issues such as heart attacks. One study even found multiple signs of heart stiffness after caffeine and nicotine use in young, seemingly healthy people, which is concerning as they are not the usual heart attack demographic. This makes caffeine and nicotine more hazardous when taken together than apart.