Five hormone systems. Same mechanism as smoking. GP first.

Nicotine affects multiple hormones in the body. The effects are well documented in smoker research plus the underlying mechanism applies whether nicotine comes from smoking or vaping. Vaping is a newer category so the direct long-term evidence base is thinner than for smoking. Here is the current picture of what nicotine does to the main hormone systems, what that means for vapers plus why personal medical advice from your GP matters for any specific hormonal concern. This article is general consumer information, not medical advice.

How nicotine interacts with the hormone system

The endocrine system is the network of glands that produce hormones plus release them into the bloodstream. Hormones coordinate almost every function in the body including stress response, metabolism, reproduction plus sleep. Nicotine is a potent stimulant that binds to specific receptors in the brain plus nervous system. The binding triggers a cascade of hormone releases. Regular nicotine use can shift the baseline activity of some hormone systems over time.

Five hormone systems are affected most clearly based on published research on smokers:

1. Cortisol (the stress hormone)

Nicotine stimulates the release of cortisol from the adrenal glands. Cortisol is the body's main stress hormone. It raises blood glucose, mobilises energy reserves plus triggers the alertness response that users notice as part of the nicotine effect. Every nicotine hit drives a short-term cortisol spike.

Over longer periods regular nicotine use is associated with elevated baseline cortisol levels in some studies. Chronic cortisol elevation has been linked with various health issues including weight gain patterns, reduced sleep quality plus cardiovascular effects. Reducing nicotine strength or quitting entirely reduces the cortisol impact.

2. Adrenaline (fight-or-flight)

Alongside cortisol, nicotine triggers the release of adrenaline and noradrenaline. These are the acute stress hormones that drive the fight-or-flight response. They raise heart rate plus blood pressure. The effect is short-term and passes within minutes of the nicotine hit. Regular nicotine users notice this as the “rush” of the first vape of the day.

3. Insulin (glucose regulation)

Nicotine reduces insulin sensitivity over time. This is covered in detail in our separate piece on can vaping affect blood sugar levels. The short version is that long-term nicotine use makes the body less responsive to insulin which matters for diabetes risk plus management. Pre-diabetic or diabetic users should always discuss nicotine use with their GP or diabetes team.

4. Sex hormones (testosterone plus oestrogen)

This is where the evidence gets more nuanced. Research on smokers has shown nicotine can affect sex hormone levels in several ways:

• Testosterone. Some studies on male smokers have shown reduced testosterone levels plus effects on sperm quality. The effect appears dose related.
• Oestrogen. Research on female smokers has shown nicotine can affect oestrogen metabolism plus menstrual cycle regularity. Some evidence links smoking to earlier menopause.
• Fertility. Both male and female fertility markers can be affected by nicotine use. This is one reason NHS pre-conception advice typically includes quitting smoking.

The direct vape-specific evidence base for these effects is more limited because vaping is a newer category. The underlying nicotine mechanism is the same which means the reasonable assumption is broadly similar effects at equivalent nicotine strengths. For anyone planning a pregnancy, experiencing fertility issues or with specific sex hormone concerns, a GP conversation is the right place to start.

5. Thyroid hormones

Some research has linked nicotine use to effects on thyroid function though the evidence is less consistent than for other hormone systems. Thyroid hormones regulate metabolism, energy plus many other processes. People with known thyroid conditions should discuss nicotine use with their GP or endocrinologist as part of ongoing care.

What switching from smoking changes

For a current smoker considering switching to vaping the nicotine-specific hormonal picture is similar. The nicotine acts the same way whether delivered by combustion or by heating. However, smoking adds significant additional hormonal effects through combustion by-products including cardiovascular effects, oxygen delivery changes plus direct toxicity to some endocrine tissues. Switching to vaping removes those combustion-specific effects while maintaining the nicotine effect.

Quitting nicotine entirely remains the cleanest hormonal outcome. NHS Stop Smoking services support both full quitting plus harm-reduction switching depending on personal goals.

Practical considerations for vapers

• Strength matters. Lower nicotine strength means less nicotine absorbed per session plus smaller hormonal impact. Stepping down from 20mg toward lower strengths over time reduces cumulative effects.
• Pregnancy is a special case. NHS guidance favours quitting nicotine entirely during pregnancy plus breastfeeding. Nicotine replacement therapy (patches, gum) is sometimes recommended if quitting cold turkey is not working.
• Fertility planning. If you are trying to conceive or are being treated for fertility, discuss nicotine use with your GP or fertility team.
• Existing endocrine conditions. Diabetes, thyroid conditions plus other hormonal disorders all benefit from clear communication with your GP about any nicotine use.

For anyone stepping down nicotine strength gradually, our nicotine salts collection covers every UK compliant strength from 20mg down to 3mg.

For the wider picture on vape and health interactions across conditions, our full health hub covers every major question UK readers ask.