Why Stroke Survivors Often Get Sick After Stroke, and Why Symptoms Can Return

Recovering from a stroke is already a major challenge. Many survivors notice another frustrating problem along the way: they seem to get sick more often, and when they do, their original stroke symptoms sometimes come back. This can be frightening, but it is also a common part of the recovery journey.

Post-Stroke Immunosuppression: A Hidden Effect of Stroke

After a stroke, the brain and immune system interact in ways that can temporarily weaken the body’s defenses. Doctors call this post-stroke immunosuppression. It means your immune system is working in a “low gear,” leaving you more vulnerable to infections.

This immune change is not just a theory. In the lab, we see it directly. When we study mice after stroke, their spleens, the body’s largest reservoir of immune cells, shrink noticeably. This happens because large numbers of lymphocytes (white blood cells that normally fight infection) die off in the days immediately following a stroke. The good news is that this loss is acute and the immune system does gradually recover, but the recovery takes time. During this vulnerable period, the body has fewer soldiers on the front line to respond to bacteria or viruses.

Scientists are learning more about the mechanisms behind this. A stroke activates the brain’s stress pathways, sending powerful signals through the nervous system to the rest of the body. These signals trigger the release of stress hormones like adrenaline and cortisol. While these hormones help the brain cope with injury, they also suppress the immune system, leading to cell death in the spleen and a weakened defense against infection.

The result is that survivors may develop infections more easily. This does not only mean serious conditions like pneumonia or urinary tract infections. It can also show up as:

• Colds and respiratory infections, since viruses have an easier time getting a foothold.

• Mouth and gum infections, because immune defenses that normally keep oral bacteria in check are weaker.

• Skin infections, especially if there are wounds or pressure sores.

  
  

This combination of nervous system signaling, hormonal changes, and loss of immune cells explains why infections of all kinds are among the most common medical complications after a stroke.

Why Infections Are More Common After Stroke

Several factors make infections more likely in stroke survivors:

• Swallowing difficulties (dysphagia) can lead to food or liquids entering the lungs, raising the risk of pneumonia.

• Reduced mobility can increase the chance of urinary tract infections or chest infections.

• Hospital treatments such as catheters or ventilators add additional risk.

• Immune suppression caused by the stroke itself makes it harder for the body to fight off germs.

  
  

Why Stroke Symptoms Can Return When You’re Sick

Many survivors notice that when they develop an infection, they suddenly feel like their stroke is happening all over again. Old symptoms, such as weakness, speech problems, or balance issues, may come back or get worse.

This is called stroke recrudescence, which means the temporary return of old stroke symptoms. It can happen when the body is under stress, such as during infection, fever, dehydration, or even lack of sleep. The good news is that these symptoms usually improve once the underlying problem is treated.

However, it is critical to remember: sometimes new or worsening symptoms are caused by another stroke. There is no way for you to know the difference on your own, which is why it is essential to seek medical help right away. Although this is understandably frightening, there is also cause for reassurance. Many episodes of symptom return turn out not to be a new stroke but instead the body’s temporary response to being sick or stressed. In most cases, once the underlying issue is treated, the symptoms fade again.

The Likely Mechanism Behind the Reappearance of Symptoms

Why do old symptoms come back when you are sick? The answer lies in the way previously injured brain tissue responds to stress. Scientists think several factors combine:

• Systemic stress and inflammation: Infections trigger the immune system to release inflammatory molecules. These signals circulate in the blood and can interfere with brain tissue that was already damaged by stroke, disrupting fragile connections.

• Fever and metabolic stress: Higher body temperature or metabolic demand makes neurons in the injured brain less able to function, so old deficits resurface.

• Blood flow and neurotransmitters: Illness can affect blood pressure, oxygen delivery, and brain chemicals like glutamate and GABA. Small changes can tip vulnerable brain circuits back into dysfunction.

• Failure of compensation: After a stroke, surrounding or opposite brain regions often “pick up the slack.” When the body is stressed, these compensatory systems can falter, revealing the underlying weakness.

  
  

In other words, the injured brain is less resilient than healthy brain tissue. Stress from illness can temporarily overwhelm it, leading to the reappearance of symptoms. Once the infection, fever, or other stressor resolves, function usually improves again.

What Survivors and Caregivers Can Do

While you cannot eliminate all risks, there are steps that help:

• Prevention: Practice good hand hygiene, maintain oral care, stay up to date on vaccines (flu, pneumonia, COVID-19), and keep moving as much as you safely can.

• Watch for early signs of infection: fever, cough, sore throat, mouth pain, burning with urination, new confusion, or sudden fatigue.

• Take symptoms seriously: If new or old stroke symptoms suddenly appear, call your doctor or emergency services immediately. It may be a temporary flare, but it could also be a new stroke.

  
  

Moving Forward

Infections are unfortunately common after stroke, but with vigilance and timely medical care, most can be treated successfully. If you notice old stroke symptoms returning when you are sick, do not panic, but also do not dismiss them. Acting quickly is always the safest choice.

Disclaimer

This article is for educational purposes only. It is not medical advice and should not replace consultation with a qualified healthcare provider. If you or a loved one experiences new or worsening stroke symptoms, seek emergency medical care right away. Even if it turns out to be a temporary return of old symptoms, it is always better to be safe.

Share Your Story

Have you experienced infections or flare-ups of old symptoms after your stroke? We’d like to hear from you. Sharing your story can help others feel less alone and give practical insights to the stroke survivor community.