Alcohol and nicotine are substances that alter the functional connectivity of the brain. These changes have been observed after pinpointing particular brain areas as well as studying the overall brain wiring structure. One property of this wiring structure is the level of randomness. Evidence strongly agrees that brain connectivity is not random, but that chemical substances can affect the connectivity structure. This work aims at studying changes in resting state functional connectivity randomness in relation to the consumption of nicotine and alcohol. Results suggest that randomness in whole brain connectivity is not affected by used substance. However, connectivity among particular brain areas does show changed randomness linked to substance use. Abnormal randomness was found between salience and default mode functional domains. This dysfunction is in line with some postulates of the network model of addiction. The study provides new information on the effects of substance use on the brain.