How long does it take for steroids to weaken the immune system?

October 8, 2025 •

4 min read

Corticosteroids are powerful medications used to treat various conditions by reducing inflammation. A key effect is their impact on the immune system. Understanding how long it takes for steroids to weaken the immune system is important for managing health risks.

Quick Summary

The timeframe for steroids to weaken immunity varies, with some effects occurring quickly and others developing over extended use. Factors like duration and steroid type significantly influence this process. Short-term use has transient effects, while long-term use poses a greater risk of infection.

Key Points

Immediate Effects: Steroids can cause a temporary drop in circulating lymphocytes within hours, which recovers in 1-2 days.
Duration Matters: Significant immunosuppression is typically linked to taking corticosteroids for over two weeks.
Chronic Use Impact: Long-term use most commonly leads to a reduction in CD4 T-cells and often a decrease in infection-fighting IgG antibodies.
Variable Timeline: The speed and degree of immune weakening depend on the duration of treatment, the type of steroid, and individual health factors.
Increased Infection Risk: Long-term steroid use makes individuals more susceptible to opportunistic infections.
Adrenal Suppression: Chronic therapy can suppress the body's own cortisol production, a condition that can persist for months after stopping the medication.
Risk Mitigation is Key: Patients can lower their infection risk through good hygiene, avoiding sick contacts, and staying current on recommended vaccinations.

Understanding Steroids and Immune Function

Corticosteroids, such as prednisone, are medications prescribed for numerous conditions due to their anti-inflammatory properties. They mimic the action of cortisol, a hormone produced naturally by the body, to reduce inflammation. A significant aspect of their function involves suppressing or weakening the immune system. Corticosteroids affect immune function by inhibiting pro-inflammatory substances and altering the behavior of white blood cells. While this suppression helps control inflammation, it also makes the body more susceptible to infections.

Immediate vs. Long-Term Effects on Immunity

The impact of steroids on the immune system can manifest quickly or develop over time, depending on the duration of therapy and the specific type of corticosteroid used.

Short-Term and Immediate Effects

Rapid changes in the immune system can be observed following corticosteroid administration. Oral corticosteroids can cause a temporary redistribution of lymphocytes, a type of white blood cell, leading to a detectable decrease in their circulation within a few hours. This initial reduction is temporary, typically returning to normal levels within 24 to 48 hours. Similarly, injected corticosteroids can affect certain immune cells and messenger substances for a short period.

Long-Term Immunosuppression

Significant and sustained immunosuppression is generally associated with prolonged use. Using oral corticosteroids for 14 days or longer is often considered a threshold for increased immunocompromise.

Chronic corticosteroid use can lead to more lasting immune system changes, such as CD4 T-cell lymphopenia, a reduction in a type of T-lymphocyte vital for immune coordination. Long-term use is also frequently linked to decreased levels of Immunoglobulin G (IgG) in the blood (hypogammaglobulinemia). This occurs because steroids can influence the production and breakdown of immunoglobulins. This prolonged immune suppression increases the risk of opportunistic infections.

Factors Influencing the Timeline and Severity

Several factors determine how quickly and significantly steroids impact the immune system:

Duration: Extended use of corticosteroids has a greater effect on the immune system than short-term use. Using them for more than two weeks is a key factor in the increased risk of immunosuppression. Chronic use can also lead to the suppression of the body's natural cortisol production, which can take time to recover after the medication is stopped.
Type of Steroid: Corticosteroids are available in various formulations, including oral, inhaled, topical, and injected, each having different absorption and systemic effects. Oral and injected forms generally have a more pronounced systemic immunosuppressive effect compared to topical or inhaled versions, although the latter can still pose some risk.
Individual Health: A person's overall health status, including age, nutritional state, and the presence of other medical conditions, can influence the extent of side effects, including immune suppression.


Feature	Short-Term Steroid Use (Less than 2 weeks)	Long-Term Steroid Use (More than 2 weeks)
Onset of Effect	Changes in lymphocyte distribution within hours, normalizing relatively quickly.	More persistent changes develop over time.
Key Immune Impact	Transient changes in circulating lymphocytes.	Potential for chronic CD4 T-cell lymphopenia and decreased IgG levels.
Infection Risk	Generally minimal increase.	Increased risk of various infections.
Adrenal Function	Typically unaffected.	Potential for adrenal suppression, which may require time for recovery after discontinuation.

Managing the Risks of a Weakened Immune System

Given the potential for increased infection risk, especially with long-term steroid therapy, taking preventative measures is important. Recommended strategies include:

Hand Hygiene: Regularly and thoroughly washing hands helps prevent the spread of germs.
Avoid Exposure: Minimizing contact with individuals who are sick can reduce the risk of infection.
Vaccinations: Maintaining current vaccinations, including the annual flu vaccine, is crucial. Discuss other relevant vaccines, such as those for pneumonia and shingles, with your healthcare provider. Note that certain types of vaccines may require careful timing or avoidance while on steroid therapy.
Healthy Lifestyle: Adopting healthy habits, including a balanced diet, regular physical activity, sufficient sleep, and managing stress, can support overall well-being.
Monitor for Infection: Be attentive to possible signs of infection, such as fever, chills, cough, sore throat, or wounds that do not heal properly, and inform your doctor promptly if they occur.

For further information on steroid-induced immune deficiency, consult authoritative resources such as the Annals of Allergy, Asthma & Immunology.

Conclusion

While steroids can cause temporary changes in the immune system within hours of initial use through altering lymphocyte distribution, a more significant state of immunosuppression, which increases the risk of infection, is typically associated with prolonged use of corticosteroids, such as for more than two weeks. Extended use can lead to persistent reductions in key immune components. The precise timeline and degree of immune weakening are influenced by the duration and type of steroid, emphasizing the need for individuals to work closely with their healthcare providers to manage potential risks effectively.

Frequently Asked Questions

Some effects, like a temporary drop in lymphocyte counts, can be seen within hours of taking an oral corticosteroid. This initial effect usually resolves within 24 to 48 hours.

Significant immunosuppression is generally associated with prolonged use of corticosteroids. Taking these medications for over 14 days is a common threshold for being considered moderately to severely immunocompromised.

The most common immune defect associated with chronic oral corticosteroid use is CD4 T-cell lymphopenia, which is a reduction in a crucial type of white blood cell.

After stopping steroids, it can take several weeks or even up to a year for the adrenal glands and immune function to fully recover, especially after long-term use. This recovery period is variable.

Oral and injected steroids typically have a greater systemic immunosuppressive effect than inhaled or topical steroids. However, all forms carry some risk, and the effects depend on the duration of use.

Signs can include an increased frequency of infections, wounds that are slow to heal, fever, chills, and persistent cough. Steroids can also mask some signs of infection, so it's important to be vigilant.

It depends on the vaccine and the steroid use. Generally, non-live vaccines like the flu shot are recommended. For live-virus vaccines, clinicians often advise waiting at least one month after stopping prolonged corticosteroid therapy.