Salbutamol and Women: Features and Risks

Salbutamol is the best-known short-acting bronchodilator, which saves millions of people with asthma from an attack of breathlessness. For women it has separate "storylines": pregnancy and breastfeeding, the connection between bronchial asthma and the menstrual cycle, former obstetric use, and the widespread practice of taking salbutamol tablets as a "fat burner." Our editorial team has examined what of this is confirmed by studies and what is a myth.

Why Women Need a Separate Conversation About Salbutamol

Salbutamol (in the US — albuterol) is a selective agonist of beta-2 adrenergic receptors. Reaching the smooth muscles of the bronchi, it activates adenylate cyclase, raises the level of cAMP in the cell and causes the muscles to relax. That is why inhalation relieves bronchospasm within a few minutes. However, beta-2 receptors are not only in the bronchi: they are present in the myocardium, skeletal muscles, liver, adipose tissue and the uterus.

The last circumstance makes the topic "salbutamol and women" not a formality. Relaxation of the smooth muscles of the uterus was once used in obstetrics to slow premature labor. The effect on skeletal muscles and adipose tissue gave rise to interest in the drug among those who want to lose weight. And hormonal fluctuations during the menstrual cycle affect the course of asthma and, accordingly, the need for a bronchodilator.

Statistically, asthma in childhood occurs more often in boys, but after puberty the picture changes: among adult patients women predominate, and a severe course is more often described in them. The reasons for this shift are still being studied, and sex hormones are considered one of the significant factors. Thus, women have to use bronchodilators for a long time, in different periods of life.

It is important to immediately distinguish between two very different situations. The first is the medical use of inhaled salbutamol for confirmed asthma, where the benefit is obvious and the risks are well studied. The second is the independent use of tablets or syrup in high doses for a non-medical purpose. The safety profile in these two cases is fundamentally different, and below we will talk about both.

The Hormonal Cycle, Asthma and Bronchodilators

In some women there is so-called perimenstrual asthma — a worsening of symptoms in the days before menstruation and in its first days. According to various estimates, a significant proportion of patients with asthma notice this phenomenon, although the exact figures in studies differ substantially due to different criteria. The practical consequence is simple: on these days the need for a "rescue" inhaler may increase.

The mechanism has not been definitively established. Discussed is the effect of fluctuations in estrogen and progesterone on the inflammatory cells of the airways, on bronchial tone and on the sensitivity of beta-2 receptors. There are also data on a change in the reaction to bronchodilators in different phases of the cycle, but they are few and do not allow unambiguous conclusions.

For clinical practice the key is different: frequent use of salbutamol is a sign of insufficient asthma control, not a reason to simply increase the number of inhalations. The GINA guidelines emphasize that treatment should not rely on a short-acting bronchodilator alone; the basis is anti-inflammatory therapy with inhaled glucocorticosteroids. If exacerbations regularly coincide with a certain phase of the cycle, it is worth keeping a symptom diary and discussing it with a doctor.

Below is a summary of the periods of a woman's life when the approach to bronchodilators has its own features.

Pregnancy, Childbirth and Breastfeeding

Uncontrolled asthma during pregnancy poses a greater threat to the mother and fetus than most drugs for its treatment. Hypoxia during a severe attack worsens the supply of oxygen to the fetus. Therefore reviews, in particular the work of Schatz and Dombrowski in the New England Journal of Medicine, emphasize: pregnant women with asthma should continue effective therapy, and inhaled short-acting beta-2 agonists remain the agent of first choice for rapid relief of symptoms.

Another story is the systemic — that is, intravenous or oral — use of beta-2 agonists to slow premature labor (tocolysis). In 2013, the European Medicines Agency restricted the use of oral and rectal forms of short-acting beta agonists in obstetrics, and allowed the injectable ones only briefly, under the supervision of a specialist. The reason was reports of serious cardiovascular complications in mothers — arrhythmias, myocardial ischemia, pulmonary edema — with the questionable effectiveness of prolonged use.

This story well illustrates the difference between inhalation and systemic administration. During inhalation a small fraction of the dose enters the bloodstream, whereas a tablet or a drip creates significantly higher concentrations of the drug in the blood. It is precisely the systemic concentrations that are responsible for tachycardia, tremor, hypokalemia and an increase in glucose levels.

During breastfeeding, inhaled salbutamol, according to available data, is considered compatible with feeding, since the amount of the substance in milk after inhalation is negligible. However, any changes in the treatment regimen during this period, as during pregnancy, should be coordinated with the doctor managing the asthma and with the obstetrician-gynecologist.

• Do not cancel the basic therapy of asthma on your own after learning that you are pregnant.
• Monitor how often a rapid-action inhaler is needed: an increase in frequency is a reason to visit a doctor.
• Remember that tablet beta agonists for "maintaining a pregnancy" are substantially restricted in Europe.

Off-Label Use for Weight Loss and Sport

In the fitness community, salbutamol in tablets is sometimes positioned as a "mild" substitute for clenbuterol — another beta-2 agonist known for its veterinary use and doping scandals. The logic is simple: stimulation of beta receptors increases energy expenditure and enhances the breakdown of fats. However, transferring this logic to real weight loss is incorrect.

The thermogenic effect of beta-2 agonists in humans is moderate and weakens over time due to receptor desensitization. At the same time, side effects — palpitations, tremor, anxiety, insomnia, muscle cramps — appear precisely at those systemic doses that could theoretically affect metabolism. For women with a smaller body mass, the same dose means a higher concentration of the drug per kilogram, and therefore a greater risk of adverse reactions.

As for athletic performance, the systematic review and meta-analysis by Pluim and colleagues (2011) found no improvement in aerobic or anaerobic performance in healthy athletes after inhalation of therapeutic doses. A later meta-analysis by Riiser and colleagues (2020) showed that an ergogenic effect on sprint and strength is possible mainly with systemic administration or doses exceeding the permitted ones. That is precisely why the World Anti-Doping Agency regulates salbutamol more strictly than it seems at first glance.

According to the WADA Prohibited List, beta-2 agonists belong to class S3. Inhaled salbutamol is permitted within the established maximum daily dose, and exceeding the threshold concentration in urine is regarded as an adverse analytical finding unless the athlete proves by a pharmacokinetic study that it is the result of a therapeutic inhalation. Tablet forms are not allowed in competition. Female athletes with asthma should find out in advance the requirements of their federation regarding documentation of the diagnosis.

Side Effects to Consider

The most frequent adverse reactions to salbutamol are a fine tremor of the hands, a rapid heartbeat, a feeling of nervousness and headache. During ordinary inhalation therapy they are usually mild and pass quickly. They manifest significantly more often and more intensely when taking tablets, syrup or with multiple inhalations in a row.

A less noticeable but important effect is a decrease in the level of potassium in the blood. Beta-2 stimulation "drives" potassium into the cells, and its concentration in the plasma falls. The classic work of Brown and colleagues in the New England Journal of Medicine as early as 1983 described this mechanism using the example of adrenaline. Hypokalemia is especially dangerous in combination with diuretics, with vomiting, diarrhea or the strict diets that women often practice during weight loss.

Cardiovascular reactions deserve separate attention in women with mitral valve prolapse, arrhythmias, hyperthyroidism, or those who simultaneously consume caffeine, fat burners with synephrine or other stimulants. The combination of several sympathomimetics enhances tachycardia and can provoke a rhythm disturbance. Salbutamol also raises glucose levels, which is important for women with diabetes mellitus, in particular gestational diabetes.

Alarming symptoms that require immediate medical attention are chest pain, a feeling of "skipped beats" in the heart, severe shortness of breath that does not pass after inhalation, muscle cramps and pronounced weakness. The absence of an effect from the usual dose of a bronchodilator during an attack is also a reason to call an ambulance, as this may indicate a severe exacerbation of asthma.

Editorial Conclusions

Inhaled salbutamol remains a safe and necessary agent for women with asthma, in particular during pregnancy. Refusing treatment out of fear of the drug usually does more harm than the drug itself.

Systemic use — tablets, syrup, injections — is associated with a noticeably higher risk to the heart, potassium and glucose levels. That is precisely why in Europe the use of beta agonists to slow labor was restricted, and for the same reason we consider the independent use of tablets "for weight loss" an unjustified risk.

If an inhaler is needed more often than usual, this is a signal to review the basic therapy of asthma, not to increase the dose of the bronchodilator.

We also recommend reading our materials about tests during the medical use of salbutamol, about clenbuterol and its effect on the heart, and about the rules of therapeutic use of prohibited substances in sport.

References

1. Global Initiative for Asthma. Global Strategy for Asthma Management and Prevention. GINA; 2024.
2. Schatz M, Dombrowski MP. Clinical practice. Asthma in pregnancy. N Engl J Med. 2009;360(18):1862–1869.
3. European Medicines Agency. Restrictions on use of short-acting beta-agonists in obstetric indications. EMA; 2013.
4. Pluim BM, de Hon O, Staal JB, et al. β2-Agonists and physical performance: a systematic review and meta-analysis of randomized controlled trials. Sports Med. 2011;41(1):39–57.
5. Riiser A, Stensrud T, Stang J, Andersen LB. Can β2-agonists have an ergogenic effect on strength, sprint or power performance? Systematic review and meta-analysis of RCTs. Br J Sports Med. 2020;54(22):1351–1359.
6. Brown MJ, Brown DC, Murphy MB. Hypokalemia from beta2-receptor stimulation by circulating epinephrine. N Engl J Med. 1983;309(23):1414–1419.
7. World Anti-Doping Agency. The World Anti-Doping Code: International Standard — Prohibited List. WADA; 2024.