Can smoking cause hormonal imbalances? Just like the negative consequences to heart and lung health, smoking can also negatively impact our reproductive health. Read on to find out. 

Quick facts:

• Cigarette smoke’s chemical components can be toxic for the body, disrupting many physiological processes, including the endocrine system.
• Both active and passive smoking can negatively impact our hormonal health.
• Smoking can disrupt our levels of many important reproductive hormones as well as our thyroid and cortisol levels.
• As well as menstrual cycle changes and fertility issues, smoking has been linked to dysmenorrhoea (7) and early onset menopause (15), due to its direct effect on ovarian follicles and oestrogen levels.
• Quitting smoking can greatly improve your chances of conceiving if you’re thinking of, or currently trying to start a family.

How smoking affects the body

It’s a well-known fact that smoking can have a negative impact on health, with both active and passive smoking being associated with multiple forms of cancer, diabetes and heart disease.

Despite this, in the UK, as of 2019, 28% of men and 22% of women aged between 25 and 34 years are current smokers, according to published health data in England (1)—and a whopping 175 million people assigned-female-at-birth (AFAB) smoke worldwide.

But whilst smoking’s effects on the heart and lungs are fairly common knowledge, fewer people are aware that it can also influence the body’s hormones.

But how exactly are hormones and smoking linked? In this article we’ll look at:

• Does smoking affect hormones?
• How does smoking affect different hormones?
• Do hormones balance after quitting smoking?

Does smoking affect hormones?

Despite the lack of public awareness, there is plenty of research that shows how smoking can impact and even wreak havoc on our hormonal health.

The chemical components of cigarette and cigar smoke can disrupt the normal functioning of our bodily systems, including the endocrine system. The endocrine system is a network of glands which influence the production, secretion and regulation of hormones throughout the body, such as the hypothalamus, thyroid, adrenal gland, and even the ovaries. 

This disruption might lead to lasting effects on all kinds of hormonally regulated processes, including sexual function and reproductive potential, our metabolism and even our sleep. 

As mentioned, both active and passive smoking (also known as second-hand smoking) can cause these nasty effects, with some research even indicating that prolonged exposure and inhalation of cigarette smoke can even affect the onset of menopause (3).

There are over 4,000 substances in cigarettes that display reproductive toxicity.

How does smoking affect different hormones?

Smoking has been linked to abnormal changes and fluctuations in various hormone levels, including:

• Testosterone
• Oestrogen 
• Follicle-stimulating hormone (FSH), 
• Luteinising hormone (LH) 
• Anti-mullerian hormone (AMH)
• Prolactin
• Thyroid hormones

Let’s take a look at each of these in detail.

Smoking and testosterone

Studies have consistently shown that smoking increases testosterone in AFAB individuals. Those who smoke have been found to have higher serum testosterone levels in their blood than those who don’t (4). 

This is because smoking is inherently pro-androgenic, meaning it has a positive effect on androgen hormones like testosterone. Increased testosterone levels can bring on side effects such as excess body hair growth (hirsutism), acne, greasy hair and skin, irregular periods and low libido.

The main reason for smoking’s pro-androgenic effects lies with nicotine. As tobacco is metabolised, the nicotine within it produces a compound known as cotinine, which inhibits testosterone breakdown (17).

However, it’s interesting to note that similar studies performed on ageing men have indicated that, over a long enough timespan, smoking can reduce testosterone levels in those assigned-male-at-birth (AMAB) (16).

Smoking and oestrogen

As well as being pro-androgenic, smoking is also anti-oestrogenic, which means it has a negative effect on oestrogen levels. Studies have shown that women who smoke have 

lower progesterone and oestrogen levels in both their blood and follicular fluid (the fluid which surrounds the developing egg, important for egg growth) (2,5). 

Smoking even affects the conversion of androstenedione to oestradiol by cells within the eggs (2). This switch is mainly driven by the effects smoking has on the production of these hormones. 

As well as negatively affecting oestrogen production and metabolism by your liver, smoking increases the levels of a hormone called sex hormone-binding globulin (SHBG) which binds to oestrogen—preventing it from performing its essential functions around the body.

Symptoms of low oestrogen can include low libido, fatigue, and negative mood changes.

Smoking and gonadotropins

Follicle-stimulating hormone (FSH) and luteinising hormone (LH) are both gonadotropin hormones. These are hormones released from the hypothalamus (a part of the brain) to regulate the menstrual cycle and induce ovulation. 

Unsurprisingly, smoking has been found to affect gonadotropin levels as well. Studies have shown that habitual smokers tend to have higher levels of FSH and LH in the first half of their cycle and during their periods, than non-smokers (6,7). 

Disrupted FSH and LH levels can lead to problems with both fertility and menopause.

Smoking and Anti-müllerian hormone

Anti-müllerian hormone (AMH) is produced by granulosa cells within the ovarian follicles. It’s used as an indicator of ovarian reserve, sometimes referred to as egg count. Research has shown that smokers generally have lower AMH levels. One study in particular found that current smokers have  44% lower AMH levels than non-smokers (8), indicating that smoking can be directly toxic to the eggs within the ovaries.

Another study showed that, in smokers, the fluid produced by the granulosa cells (known as follicular fluid) also contains increased levels of harmful nicotine toxins (9).

Chemicals derived from cigarettes and smoking have even been detected in the cervical mucus (10).

Smoking and thyroid hormones

Cigarette smoke has been found to have both inhibitory and stimulatory effects on thyroid hormones. Both active and passive smoking have been linked to decreased levels of thyroid-stimulating hormone (TSH) and increased levels of free thyroxine (T4) and triiodothyronine (T3) (11,12). 

Because the thyroid gland plays an important role in the regulation of many different bodily functions such as growth and development, disruption in thyroid level can have huge knock on effects all around the body. The thyroid can also affect fertility.Smoking is consequently a known risk factor for thyroid-related disorders, especially Grave’s disease and Goitres (13,14).

Smoking and prolactin

Prolactin is produced by the pituitary gland in the brain and is most commonly associated with milk production and altering breast physiology, but it also has a number of different roles throughout the body. 

Chronic long-term smoking has been found to be associated with decreased prolactin levels (14), which can cause irregular menstrual cycles, difficulty breastfeeding and negative mood changes.

Smoking and cortisol

Smoking has also been linked to increased cortisol levels in the blood. It also affects hormones involved in the production of cortisol (2), which can disrupt the regulation of its levels. Cortisol is a hormone released by the body in reaction to stress, leading to what is known as the fight or flight response. When in fight or flight mode, the brain uses cortisol to divert any energy away from ‘non-essential’ bodily functions.

If we continually have elevated cortisol levels in the blood, this can lead to chronic stress, impaired immune function, decreased metabolism and poor mental health.Chronic stress can affect the menstrual cycle and lead to problems with fertility, ovulation and further hormonal disruption.

How long does it take for hormones to balance after quitting smoking?

There isn’t currently much scientific research on what happens to a person’s hormones after they quit smoking. 

After a period of acute smoking, such as one or several cigarettes over the course of an evening, the body starts to cleanse itself of the toxins from cigarette smoke after as little as a few hours. As these toxins are removed from the system, their impact on certain hormones diminishes. 

However, after chronic smoking, it can take up to 20 years for the body to fully return to the state of a non-smoker. This will vary from person to person and depend on other lifestyle factors as well as medical history.

If you’re thinking about your fertility or trying to conceive soon, the good news is quitting smoking before attempting to conceive can dramatically improve the chances of getting pregnant (18).

If you need help quitting, check out these top ten tips to help you stop smoking.

If you’re worried about smoking and your hormone levels, our at-home Hormone & Fertility Test can help you to understand where your reproductive health is at, including testing for all of the hormones mentioned in this article.

Resources:

1. Statista.  Proportion of individuals who currently smoke in England in 2019, by gender and age [Online]. (2020). [Accessed 9 September 2021]. Available from: https://www.statista.com/statistics/376611/current-smoker-by-gender-and-age-in-england/. 
2. Jandíková, H, Dušková, M and Stárka, L. The influence of smoking and cessation on the human reproductive hormonal balance. Physiol Res. 2017;66(Suppl 3):S323-s31.
3. Yang, HJ, Suh, PS, Kim, SJ and Lee, SY. Effects of Smoking on Menopausal Age: Results From the Korea National Health and Nutrition Examination Survey, 2007 to 2012. J Prev Med Public Health. 2015;48(4):216-24.
4. Sowers, MF, Beebe, JL, McConnell, D, Randolph, J and Jannausch, M. Testosterone Concentrations in Women Aged 25–50 Years: Associations with Lifestyle, Body Composition, and Ovarian Status. American Journal of Epidemiology. 2001;153(3):256-64.
5. Daniel, M, Martin, AD and Drinkwater, DT. Cigarette smoking, steroid hormones, and bone mineral density in young women. Calcif Tissue Int. 1992;50(4):300-5.
6. Windham, GC, Mitchell, P, Anderson, M and Lasley, BL. Cigarette smoking and effects on hormone function in premenopausal women. Environ Health Perspect. 2005;113(10):1285-90.
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8. Plante, BJ, Cooper, GS, Baird, DD and Steiner, AZ. The impact of smoking on antimüllerian hormone levels in women aged 38 to 50 years. Menopause (New York, NY). 2010;17(3):571-6.
9. Zenzes, MT, Puy, LA and Bielecki, R. Immunodetection of benzo[a]pyrene adducts in ovarian cells of women exposed to cigarette smoke. Mol Hum Reprod. 1998;4(2):159-65.
10. Budani, MC and Tiboni, GM. Ovotoxicity of cigarette smoke: A systematic review of the literature. Reproductive Toxicology. 2017;72:164-81.
11. Soldin, OP, Goughenour, BE, Gilbert, SZ, Landy, HJ and Soldin, SJ. Thyroid hormone levels associated with active and passive cigarette smoking. Thyroid. 2009;19(8):817-23.
12. Zhang, Y, Shi, L, Zhang, Q, Peng, N, Chen, L, Lian, X, Liu, C, Shan, Z, Shi, B, Tong, N, Wang, S, Weng, J, Zhao, J and Teng, W. The association between cigarette smoking and serum thyroid stimulating hormone, thyroid peroxidase antibodies and thyroglobulin antibodies levels in Chinese residents: A cross-sectional study in 10 cities. PLOS ONE. 2019;14(11):e0225435.
13. Kapoor, D and Jones, TH. Smoking and hormones in health and endocrine disorders. European Journal of Endocrinology eur j endocrinol. 2005;152(4):491-9.
14. Tweed, JO, Hsia, SH, Lutfy, K and Friedman, TC. The endocrine effects of nicotine and cigarette smoke. Trends Endocrinol Metab. 2012;23(7):334-42.
15. Yang, HJ, Suh, PS, Kim, SJ and Lee, SY. Effects of Smoking on Menopausal Age: Results From the Korea National Health and Nutrition Examination Survey, 2007 to 2012. J Prev Med Public Health. 2015;48(4):216-24.