India is seeing a rise in seasonal influenza, with H1N1 accounting for much of the increase in influenza A infections. The Indian Medical Association (IMA) has urged people to avoid self-medication with antibiotics and antivirals, warning that unnecessary use of medicines during the current flu surge can cause harm and contribute to antimicrobial resistance (AMR). The advisory comes amid a rise in influenza cases during the monsoon period, with Delhi alone reporting more than 1,770 laboratory-confirmed H1N1 cases this year. 

The IMA has also said there is no evidence that a new genetic mutation or new strain of H1N1 is driving the current increase. The medical body described the situation as a seasonal surge and said most infections are mild and self-limiting. Typical symptoms include sudden fever and chills, dry cough, sore throat, body aches, fatigue, headache and a runny or blocked nose. Children may also experience nausea, vomiting or diarrhoea. Importantly, H1N1 is caused by an influenza virus, and antibiotics such as azithromycin, amoxicillin-clavulanate and cefixime do not treat viral infections. 

We spoke to Dr Aishwarya R, Consultant – Infectious Diseases, Aster Whitefield Hospital, to understand why antibiotics do not work against H1N1, why people may continue to feel unwell despite taking them, when antibiotics may actually be required and how inappropriate antibiotic use contributes to antimicrobial resistance.

Why antibiotics do not work against H1N1

According to Dr Aishwarya, one of the common responses to the sudden onset of fever, body ache, cough and weakness is to take an antibiotic without first establishing what is causing the illness. In India, she said, self-medication with antibiotics is common, particularly when respiratory symptoms appear severe.

However, if the illness is caused by H1N1, taking an antibiotic will not treat the underlying infection. “It is worth noting one key point: H1N1 is a sickness that is caused by a viral infection. The antibiotic has no impact whatsoever on the virus or on reducing the symptoms related to the fever,” she said.

This distinction between viral and bacterial infections is crucial. Antibiotics are medicines designed to act against bacteria; influenza viruses are biologically different pathogens and are not killed by antibiotics. Therefore, taking an antibiotic for uncomplicated influenza does not shorten the viral illness or directly relieve symptoms such as fever, cough, muscle aches or fatigue.

Dr Aishwarya explained that this can also create confusion for patients. A person who takes an antibiotic while suffering from H1N1 may continue to have fever and weakness because the virus is still running its course. Instead of recognising that the medicine was never expected to work against the virus, the patient may conclude that the antibiotic was “not strong enough” and switch to another medicine or take a higher amount.

“That creates a vicious cycle of taking unnecessary drugs,” she said.

Fever, chills, body aches and fatigue are part of the illness and the body’s immune response to the viral infection. Their persistence does not necessarily mean that an antibiotic has failed. More importantly, changing or adding antibiotics without medical advice can expose patients to unnecessary side effects while delaying appropriate medical assessment.

For influenza itself, antiviral medicines are a different category from antibiotics. Whether an antiviral is appropriate depends on factors including the severity of illness, the patient’s risk factors and how early treatment is started. Antibiotics should not be substituted for antivirals, nor should either category of medicine be taken without appropriate medical advice.

How unnecessary antibiotics can make you feel worse

Taking an antibiotic unnecessarily does not simply mean that the medicine will have no benefit. It can also cause side effects while a person is already dealing with an infection.

Dr Aishwarya said antibiotics can cause nausea, vomiting, abdominal discomfort and diarrhoea. These effects can occur because antibiotics affect bacteria beyond the organisms that may be causing a bacterial infection, including bacteria that form part of the body’s normal microbiota.

This can be particularly problematic for someone with influenza. The person may already be experiencing weakness, poor appetite, fever or dehydration, and gastrointestinal side effects from an unnecessary antibiotic can add to the burden.

“In other words, a patient suffering from H1N1 virus will be feeling weak due to the disease while simultaneously suffering from digestive issues caused by unnecessary medication,” she said. In some cases, she added, significant vomiting or diarrhoea can contribute to dehydration.

Antibiotics can also cause allergic reactions, ranging from relatively mild skin rashes to more serious reactions. Less commonly, antibiotic exposure can be associated with infection caused by Clostridioides difficile, a bacterium that can cause significant diarrhoea and inflammation of the colon.

This is why the decision to prescribe an antibiotic should be based on an assessment of whether there is a bacterial infection that is likely to benefit from treatment. The presence of fever or cough alone does not establish that antibiotics are necessary.

The problem becomes particularly important during periods when respiratory infections are circulating widely. When several people in a household or community develop similar flu-like symptoms, there can be a tendency to assume that antibiotics are required. But the symptoms themselves cannot determine whether the infection is viral or bacterial.

The bigger concern: Antibiotic resistance

Beyond the immediate side effects, inappropriate antibiotic use contributes to a much larger public health problem: antimicrobial resistance.

Dr Aishwarya pointed out that AMR is often misunderstood. It is not the human body that becomes resistant to an antibiotic. Rather, bacteria can develop or acquire mechanisms that allow them to survive exposure to medicines that would previously have killed them or stopped their growth.

“One of the many misconceptions is that the human body develops AMR. The reality is that the bacteria are the ones that can be resistant to the antibiotics,” she said.

When antibiotics are used unnecessarily or inappropriately, susceptible bacteria can be eliminated while bacteria with resistance mechanisms may survive and multiply. Over time, this can make bacterial infections harder to treat.

“Using antibiotics improperly means that there will be the presence of bacteria which are susceptible to the drugs, whereas the bacteria that possess resistance will survive and reproduce,” Dr Aishwarya explained.

The consequences extend beyond the individual taking the medicine. Resistant bacteria can spread between people and communities, meaning that inappropriate antibiotic use can contribute to a wider pool of drug-resistant infections.

In practical terms, this can leave doctors with fewer effective options when a person actually develops a bacterial infection requiring treatment. Some infections may then require medicines that are more complex, more expensive or associated with greater side effects.

This is why antibiotics should be viewed as targeted medicines rather than general-purpose drugs for fever, cough or weakness. Taking them without a clear indication does not provide additional protection against influenza and can create risks that may only become apparent later.

When antibiotics may actually be needed during H1N1

The message that antibiotics do not treat H1N1 does not mean that a person with influenza can never require an antibiotic.

“Influenza can sometimes be complicated by a secondary bacterial infection. Bacterial pneumonia is one example. In such cases, a doctor may determine that antibiotic treatment is necessary. The important point is that the antibiotic is being prescribed because of the bacterial infection or complication, rather than because H1N1 itself is a virus,” she said. 

Patients should therefore not use leftover antibiotics from an earlier illness or start a medicine recommended for someone else simply because flu symptoms appear severe.

Certain changes in symptoms should prompt medical assessment. These include increasing difficulty in breathing, chest pain, a worsening cough, persistent or worsening fever, or deterioration after an initial period of improvement. Such symptoms do not automatically mean that a bacterial infection is present, but they warrant clinical evaluation to determine the cause and appropriate treatment.

“The right antibiotic to use depends on the source of the infection, and in the case of viral infection, an antibiotic is never the solution,” Dr Aishwarya concluded.