Low blood pressure, or hypotension, is not always a cause for concern, but a sudden drop can signal a medical emergency, particularly when caused by significant blood or fluid loss, a cardiologist has warned.

Director of Hypertension, Nigerian Heart Foundation (NHF), Prof. Austine Obasohan, told The Guardian that heavy bleeding from accidents or menstruation, severe dehydration caused by vomiting or diarrhoea, illnesses such as cholera, and excessive doses of blood pressure medication can cause a dangerous fall in blood pressure.

He said a person whose usual blood pressure is about 120/80mmHg but suddenly records 90/50mmHg after substantial blood or fluid loss requires urgent medical attention and appropriate fluid or blood replacement.

However, Obasohan cautioned against treating every low blood pressure reading as a disease, saying some healthy people naturally have readings below the conventional 100/60mmHg threshold without symptoms or health complications.

He said doctors are more concerned about why blood pressure is low, whether it has fallen suddenly and whether the individual has symptoms than about the numerical reading alone.

A person whose blood pressure is naturally around 90/60mmHg but who feels well, remains active and has no underlying illness may not require treatment, he said.

“If your blood pressure is low, whether it is 90/70, 100/70, and you have no complaint, we say congratulations,” Obasohan said, explaining that lower blood pressure is generally associated with a lower risk of cardiovascular disease.

He noted that some populations living in rural or less urbanised environments have historically recorded relatively low blood pressure without suffering the cardiovascular complications associated with hypertension.

He cited observations among the Koma people in northern Nigeria, whose blood pressure, he said, has been recorded at around 90/60mmHg despite being healthy and physically active. He also referred to the Samburu people of East Africa.

Obasohan said increasing urbanisation and modern lifestyles have contributed more significantly to rising blood pressure and cardiovascular disease. “In cardiovascular medicine, we will say the lower your blood pressure is, the better for you, provided you probably do not stand too long,” he added.

He explained that some people with naturally low blood pressure may experience dizziness after standing for a prolonged period because the cardiovascular system must work against gravity to maintain adequate blood flow to the brain.

“You will see some people who, when they stand for a long time, may start to feel dizzy because the heart is doing more work to pump the blood to the brain,” he said.

He advised such individuals to sit down when they feel dizzy rather than attempting to raise their blood pressure unnecessarily.

The cardiologist also warned against deliberately consuming large amounts of salt, salty foods or salt water to raise blood pressure when there is no medical indication.

He said salt or fluid replacement may be necessary when blood pressure falls because of significant fluid loss, but it is not appropriate for someone whose blood pressure is naturally low and who has no symptoms. “It is not necessary at all. It is wrong, as long as they do not have any problem,” he said.

Another situation requiring urgent attention, he said, is a sudden fall in blood pressure caused by taking more antihypertensive medication than prescribed.

Obasohan gave the example of someone whose usual blood pressure is about 130/80mmHg but who accidentally takes an excessive dose and subsequently experiences a significant drop. “That becomes a problem for you because the blood pressure suddenly drops because you took an excessive dose of your medications,” he said.

He stressed that such a drop is different from a person who has consistently recorded relatively low blood pressure without symptoms. Treating the reading without identifying its cause, he said, could lead to unnecessary or inappropriate intervention.

Obasohan also distinguished hypotension from hypoglycaemia, or low blood sugar, saying the two conditions should not be confused. Unlike naturally low blood pressure, significantly low blood sugar can rapidly become a medical emergency because the brain depends heavily on glucose to function.

“When the sugar in the body is low, the brain is deprived of its substrate for performing. And it cannot perform. Before you know it, the person goes unconscious,” he said.

He explained that severe hypoglycaemia can cause confusion, seizures, unconsciousness, permanent brain damage or death if not promptly corrected. Early symptoms may include sweating, trembling, nervousness and a rapid heartbeat, which occur as the body releases adrenaline in response to falling blood glucose.

He said treatment involves promptly restoring blood sugar, either orally where appropriate or through medical intervention in severe cases. For people who consistently record blood pressure below 100/60mmHg, Obasohan’s central message is that the reading alone does not necessarily indicate illness.

However, a sudden fall, particularly when accompanied by dizziness, weakness, fainting or other symptoms after significant bleeding, vomiting, diarrhoea, dehydration, severe illness or excessive medication, requires prompt medical assessment.

In such cases, he said, attention should focus on identifying and treating the underlying cause rather than simply trying to raise the blood pressure.

While hypertension remains a major public health concern because of its often silent damage to the heart, brain, kidneys and blood vessels, naturally low blood pressure should not automatically be regarded as a disease requiring treatment or dietary intervention.