Nicotine or its primary metabolite, cotinine are most often tested to evaluate tobacco use. Long term use of tobacco products can increase the risk of developing many diseases including lung cancer, COPD, stroke, heart disease, and respiratory infections, or exacerbate asthma, and blood clot formation. In pregnant women, smoking can retard fetal growth and lead to low birth weight babies.

Because use of tobacco products can greatly affect the health of individuals, companies may use nicotine/cotinine testing to evaluate prospective employees for tobacco use. Many health and life insurance companies test applicants for nicotine or cotinine as well.

Nicotine and cotinine can both be measured qualitatively or quantitatively. Quantitative testing can help distinguish between active smokers, tobacco users who have recently quit, non-tobacco-users who have been exposed to significant environmental tobacco smoke, and non-users who have not been exposed.

Cotinine may also be measured in saliva and in hair, although hair testing is primarily used in a research setting, such as a study of non-smokers exposure to tobacco smoke.

Blood or urine nicotine may be ordered by itself or along with cotinine if a doctor suspects that someone is experiencing a nicotine overdose.

When a patient has reported that they are using nicotine replacement products but are no longer smoking, nicotine, cotinine, and urine anabasine measurements may sometimes be ordered. Anabasine is present in tobacco but not in commercial nicotine replacement products. If a sample tests positive for anabasine, then the person is still using tobacco products.

Cotinine and/or nicotine may be ordered whenever an evaluation of tobacco use status or tobacco smoke exposure is required. When a person enters a smoking cessation programme, blood or urine cotinine tests may be ordered to evaluate compliance. Urine, blood, or saliva testing may be performed as a screen for tobacco use when someone is applying for life or health insurance, or applying for work with an employer that prohibits smoking. Testing may also be ordered by a court for child custody purposes. Since smoking can increase the risks of medical complications, testing may be performed prior to the start of some drug therapies or surgical procedures.

Nicotine and cotinine are sometimes measured when a patient has symptoms that the doctor suspects may be due to a nicotine overdose. Symptoms of mild nicotine poisoning may include:

• Nausea, vomiting
• Dizziness
• Drooling
• Weakness

More serious nicotine poisoning may result in:

• Increased blood pressure and/or heart rate, which then suddenly drops
• Slowed or difficulty breathing
• Seizures
• Coma

Hair testing is rarely performed in a clinical setting but may be ordered when an evaluation of longer term tobacco use is desired.

In the blood, nicotine levels can rise within a few seconds of a puff on a cigarette. The quantity depends on the amount of nicotine in the cigarette and the manner in which a person smokes, such as how deeply they inhale. Test results are not interchangeable. Concentrations will be higher in urine than in blood or saliva. There is also some variability from person to person and some genetic differences in the rate that nicotine is metabolised and in the rate that cotinine is cleared from the body. When someone stops using tobacco and nicotine products, it can take more than two weeks for blood levels of cotinine to drop to the level that a non-tobacco user would have and several weeks more for urine levels to decrease to very low concentrations.

In general, high levels of nicotine or cotinine indicate active tobacco or nicotine replacement use. Moderate concentrations indicate a tobacco user who has not had tobacco or nicotine for two to three weeks. Lower levels may be found in a non-tobacco user who has been exposed to environmental smoke. Very low to non-detectable concentrations are found in non-tobacco users who have not been exposed to environmental smoke or a tobacco user who has refrained from tobacco and nicotine for several weeks.

Patients whose nicotine overdose is self-evident may not be tested for nicotine or cotinine. Concentrations would typically be increased, but levels do not necessarily correlate with the severity of a person's symptoms.

About Reference Intervals

Some pesticides contain high concentrations of nicotine. This can be another source of nicotine poisoning.

Nicotine is found not just in the tobacco plant but also in other plants in the same family. These include potatoes, tomatoes, eggplants, and red peppers. The concentration of nicotine in these plants, however, is much lower than that in tobacco. 

A person's genetic makeup may influence how they metabolise nicotine. Variations in the genes that code for the CYP2A6 and CYP2B6 liver enzyme affect the rate of nicotine metabolism (for more on this, see Pharmacogenomics).

E-cigarettes and other electronic nicotine delivery systems (ENDS) use concentrated liquids that are heated to produce a vapour that is then inhaled. The concentrations may contain nicotine, nicotine and flavourings, or just flavourings. If nicotine is present in the concentrate, then it may be detected in your system. This concentrate also poses a risk for accidental nicotine poisoning. The ENDS products are currently thought to be less harmful than smoking, but the medical community is concerned about their growing popularity. Because they are relatively new, their long-term health effects have yet to be determined.

There are many national organisation and government resources available. See the links on the related information page below for more information.