There are at least two ways that drugs can vary in their addictive potential. One is the drug’s half-life, which refers to the time it takes for the drug to pass through the body. Drugs with a short half-life often have very quick effects, but also have sharp withdrawal reactions, which can contribute to addiction. Drugs with longer half-lives have a less quick and intense high and cause less abrupt withdrawal syndromes. However, their withdrawal syndromes can last longer as it takes more time for the drug to fully clear the system. The intensity of the dopamine spike that a drug causes also affects its addiction potential. Although drugs such as cocaine, nicotine, and amphetamine all cause an increase in dopamine activity, they vary tremendously in terms of the strength of the spikes they cause.