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Still feel unwell after testing negative for COVID-19? How to manage post-infection symptoms

SINGAPORE: Although more than 99 per cent of COVID-19 cases in Singapore in recent weeks are considered mild infections, some people have experienced lasting symptoms even after testing negative for the coronavirus.

Patients have reported persistent coughs and airway irritation, breathlessness, fatigue, brain fog, palpitations, chest tightness or pain, and digestive issues such as acid reflux and not being able to tolerate food that they could eat before.

There can also be a negative impact on mental well-being, said Dr John Cheng, Head of Primary Care at Healthway Medical Group.

Local data from the National Centre for Infectious Diseases (NCID) last year showed that 16.9 per cent of a group of COVID-19 patients – who were unvaccinated – reported persistent symptoms at 30 days post-infection. And 11.7 per cent reported symptoms six months after contracting the virus, said Dr Edgar Tay, a cardiologist at the Asian Heart & Vascular Centre, Mount Elizabeth Hospital.

He added that data suggests these symptoms may be reduced in those who were vaccinated. Previously termed “long COVID”, the condition has recently been renamed post-acute sequelae of SARS-CoV-2 Infection (PASC).

CNA asked some medical professionals how people can manage such post-COVID symptoms:


Physiotherapist Jaclyn Chow said that inflammation in the cells infected by the SARS-CoV-2 virus can persist even after one tests negative, leading to lingering symptoms like a cough, airway sensitivity and discomfort in the upper respiratory tract.

If the cough is leading to sleeplessness or discomfort, cough medication can help to relieve the symptom. Pharmacists or doctors can recommend the appropriate medicine based on the cause of the cough, its duration and other clinical signs such as fever or muscle ache, said community pharmacist Shawn Lee. 

In most cases, cough mixtures given at the clinic are similar to what is sold at retail pharmacies, said Mr Lee, a member of the Pharmaceutical Society of Singapore. But note that these medicines do not cure the viral infection, he added. 

If the patient coughs more when lying down, it could be caused by watery mucus dripping down the back of the throat. In such cases, consider sleeping with an additional pillow to prop up the head or take an antihistamine, which is typically used for runny nose. 


A good way to manage breathlessness is to make sure one is breathing well. 

Ms Chow said that some people develop a different breathing pattern after COVID-19, and start breathing with their mouth as their nose was blocked.

But breathing through the nose warms and moistens the air, while air breathed through the mouth can be “more of an irritant”. Breathing through the nose also produces nitric oxide, which opens up the airways.

For people who are mouth breathers, she will first train them to go back to nasal breathing.

She will also make sure that they are breathing using their diaphragm rather than their upper chest. Diaphragmatic breathing is more efficient and leads to less fatigue, she said.

Posture is important as hunching limits the flexibility of one’s chest walls, and one’s breathing capacity. Chest stretches can help with this.

Improving posture can add up to 50ml of air per breath, or about 10 per cent of one’s usual air intake, said Ms Chow.

When patients start breathing better, she recommends exercises to help them regain stamina. Using one’s muscles increases oxidative capacity, or their ability to use oxygen, she added.


There can be many factors leading to fatigue but breathing exercises can help some patients deal with this, said Ms Chow.

A patient who breathes at a fast rate lowers the carbon dioxide level in their blood, causing narrowing of airways and blood vessels. If the level is far too low, it can limit blood flow to the brain causing headaches, fatigue and dizziness.

“We try to slow the breathing rate … so that you can reverse the blood vessels narrowing, the airways narrowing and that helps with the symptoms of fatigue, if the cause is a breathing pattern disorder,” she said.

(File photo: iStock)

Healthway’s Dr Cheng said that for fatigue and reduced exercise tolerance, a gradual plan to recover and not over-exert the body is recommended.

“There should be a gradual return to the usual activity programme based on level of fatigue experienced by the patient. We also recommend taking regular breaks in between exercise or strenuous activities.”


With cardiac symptoms, the most important aspect is to ascertain that there are no serious cardiac conditions in patients with persistent symptoms, said Dr Tay. 

“Some patients with pre-existing cardiac illnesses may also be more symptomatic after COVID 19. So being vigilant here is important.” 

The risk of cardiovascular events may also increase after COVID-19 infection. Patients should monitor for the following:
• Any new type/new onset of chest pain
• Worsening of chest pain, shortness of breath or any new symptoms of feeling unwell

There are no standard recommendations, but it is better to seek medical attention if there are other persistent symptoms lasting beyond four to six weeks, experts said.

For patients who remain symptomatic after ruling out serious illnesses, a test such as cardiopulmonary exercise testing may be useful. 

This can shed light on whether the lung or heart or deconditioning is causing the patient’s symptoms. Following this, cardiac rehabilitation may be useful, said Dr Tay. Tailored exercises to patients’ symptoms are important, he added.


Respiratory specialist Dr Adrian Chan advised patients to seek medical evaluation if symptoms are more severe and are not improving despite recovering from COVID-19.  

If a patient reports a pulse oximeter reading of 94 per cent and below, they should seek medical advice as it may be an indication of "residual lower respiratory tract involvement by COVID", said Dr Chan, who is from Respiratory Medical Associates, Mount Elizabeth Novena Hospital.

Dr Tay also recommended seeking help if symptoms impact patients such as by affecting sleep or limiting exercise.

(File photo: iStock/Tirachard)

Post-recovery patients planning to start or resume strenuous exercise should consider a further evaluation if they have residual symptoms such as chest pain or tightness, he said.

“There is a group of patients who may have myocarditis following COVID-19 infection which would require treatment and temporary avoidance of exercise,” he said. 

He added that there could be pre-existing heart conditions brought to light following COVID-19 which warrant treatment.


Dr Chan said that most patients will recover with time, but patients should manage their symptoms to optimise function and quality of life during the period of symptoms. 

As mentioned, these measures can include breathing exercises, a gradual return to physical activities or medications to treat upper respiratory tract symptoms. 

“The optimal approach can be tailored according to the advice from the specialist,” he said.

Dr Cheng said that his general advice would include keeping up a healthy lifestyle and getting enough sleep and hydration.

“The best way to reduce risk of persistent symptoms still boils downs to the basics – prevention is still the key. Some of our suggestions include: Maintaining an active and healthy lifestyle for better immunity and easier recovery period; getting vaccinated against COVID-19 including the booster shot.” 

This is as studies have suggested that vaccination reduces the risk and severity of persistent symptoms.

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Source: CNA/hm(cy)


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