In few days after starting to smoke and after just a few cigarettes the first symptoms can appear. For some people, however, symptoms may persist for months.

Nicotine addiction diagnosis criteria for this include any 3 of the following within a 1-year time span:
• smoking more than usual;
• a habit to nicotine with decreased effect and increasing dose to obtain same effect;
• continuing to smoke in spite of health risk;
• symptoms of withdrawal after interruption;
• unceasing desire to smoke;
• spending free time smoking;
• set aside work and other events in order to smoke.

 Nicotine withdrawal symptoms include:
• tiredness;
• difficulty with concentrating;
• irritability;
• increased appetite and weight gain;
• decreased heart rate;
• depression, feelings of anger and  frustration;
• giddiness;
• restlessness; 
• trouble sleeping.

Symptoms of nicotine toxicity include:
• abdominal pain;
 • nausea;
• diarrhea;
• vomiting;
• salivation;
• paleness;
• cold sweat.

Physical effects of nicotine use include:
• accelerated blood pressure;
• increased heart rate;
• weight loss.