No pharmaceutical opinion available for this interaction.


Cobicistat can inhibit the metabolism (CYP 3A4) and increase the plasma concentration of Fluticasone.


Pharmacodynamic effects


Alternative solution(s)


Pharmacodynamic effects

Possible increase in adverse effects associated with corticosteroids.

Risk of hypercortisolism. Risk of adrenal insufficiency.


Avoid association. Choose an alternative.

Alternative solution(s)

Beclomethasone 100 μg = fluticasone 125 μg.


Fluticasone toxicity : Cushing's syndrome (moon face, buffalo hump, obesity, striations, acne, hirsutism, hypertension, osteoporosis, glucose intolerance, increased risk of infections) and adrenal suppression (melanodermia, fatigue, weakness, hypotension, weight loss, digestive disorders).



Cortisol (plasma)

Pharmacokinetic parameters


See ritonavir + fluticasone.

The pharmacokinetics of fluticasone (cytochrome 3A4 metabolism, long half-life, bioavailability, volume of distribution, lipophilicity, etc.) can lead to accumulation in the presence of CYP3A4 inhibitors.

The accumulation of corticosteroids can cause Cushing's syndrome (moon face, excitation/insomnia, hypertension, increased appetite and weight, ease of doing bruising) and potentially a suppression of the hypothalamic-pituitary axis, which could lead to adrenal insufficiency. Several cases have been reported in the literature, and this in such a short time as 2 weeks.

A pharmacokinetic study demonstrated that ritonavir, a potent CYP 3A4 inhibitor, can increase fluticasone AUC up to 350-fold.

This interaction has been notably a Health Canada warning in 2004 and ritonavir monograph specifie that its association with fluticasone is a risk of serious side effects.

The safest corticosteroid is beclomethasone (Qvar) since its metabolism is mainly by an esterification mechanism.

Ref #2550 and #2551 : A cross-sectional study (n = 11 783) suggests lower prevalence of adrenal insufficiency with beclomethasone than with other corticosteroids currently available on the market. Pharmacokinetic studies with beclomethasone and ritonavir or combination darunavir/ritonavir demonstrated that there were no clinically significant pharmacokinetic interactions. No variation of blood cortisol have been observed.

Fluticasone should not be stopped without consultation with a physician. If the axis hypothalamo-hypophyseal is eliminated, stopping suddenly fluticasone can lead to signs and symptoms of adrenal incapacity. It is recommended to decrease slowly the corticosteroid to avoid the symptoms of craving (fatigue, loss of weight, intoxications, weakness, low postural blood pressure and acute adrenal crisis). Plasma cortisol and ACTH test will document the presence or absence of adrenal insufficiency.

  • 2949
    Cobicistat (Tybost), European public assessment report (EPAR) Product Information, London, United Kingdom, 4 juin 2015.
  • 2806
    Saberi P, Phengrasamy T and Nguyen DP. Inhaled corticosteroid use in HIV-positive individuals taking protease inhibitors : a review of pharmacokinetics, case reports and clinical management. HIV medicine 2013 : 1-11.
  • 2637
    Santé Canada. Renseignements importants sur l'innocuité-interaction médicamenteuse entre le propionate de fluticasone (Flonase /Flovent /Advair ) et le ritonavir (Norvir /Kaletra). Disponible : Publié 22 janvier 2004. Consulté le 18 juin 2015.
  • 2810
    Fluticasone (Flovent HFA/Diskus), GlaxoSmithKline, Ontario, Canada, 26 avril 2018.
  • 2808
    Molimard M, Girodet PO, Pollet C et al. Inhaled corticosteroids and adrenal insufficiency: prevalence and clinical presentation. Drug Saf 2008; 31(9): 769-774.
  • 2551
    Boyd A, Hadigan C, Pau A. Darunavir/ritonavir Does Not Significantly Increase Plasma Concentrations of Orally Inhaled Beclomethasone in Healthy Volunteers. Conference on Retroviruses and Opportunistic Infections, Seattle, 2012, Abstract 611.
  • 2550
    Boyd A, Penzak S, Nieman L et al. Co-administration of Orally Inhaled Beclomethasone Dipropionate and HIV Protease Inhibitor Does Not Significantly Alter Adrenal Function in Healthy Volunteers. Conference on Retroviruses and Opportunistic Infections, Seattle, 2012, Abstract 610.
  • 3101
    Lougheed MD, Lemiere C, Ducharme F et al. Canadien Thoracic Society 2012 guideline update: Diagnosis and management of athsma in preschoolers, children and adults. Can Respir J 2012; 19 (2): 127-164.