Infusion/IV Therapy

Infusion or IV (intravenous) therapy is a treatment that delivers fluids, medicines, or nutrients directly into a vein through a small plastic tube called a cannula (a thin, flexible needle that sits just under the skin).

Because the substance goes straight into the bloodstream, the body receives it faster and more completely than it would from a tablet or injection into muscle. This matters when a patient cannot swallow, needs large amounts of fluid quickly, or requires a medicine that breaks down in the stomach before it can work.

IV therapy is used across a wide range of medical situations where the body needs something delivered quickly, reliably, or in large volume. A doctor will recommend it when the oral route (swallowing) is not possible, not fast enough, or not effective enough.

• Severe dehydration (dangerous loss of body fluids) caused by vomiting, diarrhoea, or fever
• Infections requiring intravenous antibiotics, such as sepsis (a life-threatening blood infection) or severe pneumonia (lung infection)
• Electrolyte imbalances (dangerously low or high levels of salts like sodium or potassium in the blood)
• Chemotherapy (cancer-killing medicine) for many types of cancer
• Nutritional support when a patient cannot eat — known as parenteral nutrition (feeding directly into the bloodstream)
• Pain management when oral painkillers are insufficient or cannot be swallowed
• Blood transfusions and infusions of blood products such as platelets (cells that help clotting) or plasma
• Chronic (long-term) conditions such as immune disorders requiring regular infusions of immunoglobulin (protective proteins from donated blood)
• Rapid correction of low blood sugar (hypoglycaemia) or other acute metabolic emergencies
• Preparation for surgery or support during recovery from a major procedure

IV therapy is not suitable in every situation. Doctors will usually consider an alternative when the patient is stable and can absorb medicines or fluids by mouth, or when the risks of placing a cannula — such as infection at the site — outweigh the benefit. Patients with very fragile or collapsed veins may need a special central line (a larger tube placed in a bigger vein near the heart) instead of a standard peripheral cannula.

IV therapy is generally well tolerated, but like any procedure that breaks the skin and enters a blood vessel, it carries some recognised risks.

• Pain or bruising at the cannula insertion site — the most common experience
• Infiltration (the fluid leaks out of the vein into surrounding tissue), causing swelling and discomfort around the site
• Phlebitis (inflammation of the vein), felt as redness, warmth, and tenderness along the vein
• Local infection at the skin entry point, which can usually be prevented with careful sterile technique
• Bloodstream infection (rare but serious if the cannula stays in place for many days without being changed)
• Air embolism (a bubble of air entering the vein) — very rare with modern equipment and trained staff
• Fluid overload (too much fluid given too quickly), which can strain the heart and lungs, especially in elderly patients or those with heart failure
• Allergic reaction to a specific medicine or fluid being infused — ranges from mild skin redness to a rare severe reaction
• Needle-stick injury to staff during insertion — not a risk to the patient but mentioned for completeness

Preparation for IV therapy depends heavily on what is being infused and why. For a straightforward rehydration drip in an emergency, almost no preparation is needed. For a planned infusion such as chemotherapy or an immunoglobulin infusion, the steps below typically apply. Your care team will give you specific instructions for your situation.

Before the infusion, the medical team usually considers the following:

• Fasting: For most infusions, fasting is not required. If you are also having sedation (medicine to make you drowsy and relaxed) alongside the infusion, your doctor may ask you not to eat or drink for a number of hours beforehand.
• Medications: Tell your doctor about all medicines you are taking, including herbal supplements. Some blood thinners or medicines that affect the kidneys may need to be paused before certain infusions.
• Alcohol and smoking: Alcohol can worsen dehydration and interact with some infused medicines. Smoking can make veins harder to access. Your care team may advise you to avoid both before a planned infusion.
• Hydration: For some planned infusions, drinking enough water beforehand can make veins easier to find and reduce side effects.

Tests that are commonly run before or alongside IV therapy include:

• Blood tests to check kidney function, electrolyte (salt) levels, and blood cell counts
• Blood type and cross-match if a transfusion is planned
• Allergy history review, especially for medicines to be infused
• Baseline observations: blood pressure, heart rate, temperature, and weight

During the procedure itself, the steps typically follow this order, though the exact process varies by hospital and by what is being infused:

• 1. You are made comfortable, usually sitting or lying on a bed or reclining chair.
• 2. The nurse or doctor selects a suitable vein, most often on the back of the hand or inside the forearm.
• 3. The skin over the vein is cleaned with an antiseptic (germ-killing) wipe.
• 4. A cannula is inserted into the vein. You will feel a brief sharp sting.
• 5. The cannula is secured with a small dressing (adhesive bandage) to keep it in place.
• 6. The infusion bag or syringe containing the fluid or medicine is connected to the cannula via a drip line (a long thin tube).
• 7. The flow rate is set by the nurse, either manually with a roller clamp or automatically with an infusion pump (a device that controls the exact speed of the drip).
• 8. A nurse monitors you regularly during the infusion for any signs of reaction or discomfort.
• 9. When the infusion is complete, the line is flushed (rinsed through with plain saline solution) and the cannula is either removed or capped for future use.

Recovery after a single IV infusion is usually straightforward. Most patients feel little or no different once the cannula is removed, though some — particularly those receiving chemotherapy or certain biological medicines — may feel fatigued (very tired) or unwell for a day or more. Your care team will advise you based on what was infused.

• Monitoring: After the infusion ends, you are usually observed for a short period — often between 15 minutes and an hour — to make sure there is no delayed reaction before you leave.
• Cannula site care: Once the cannula is removed, light pressure is applied to stop any bleeding. Keep the small dressing on for a few hours. If you notice increasing redness, warmth, swelling, or discharge at the site in the following days, inform your doctor.
• Activity: For a straightforward hydration or antibiotic infusion, there are usually no activity restrictions once you leave. For chemotherapy or infusions of powerful medicines, your doctor will specify how much rest is advised.
• Driving: If you received any sedation alongside your infusion, do not drive until your doctor confirms it is safe — usually at least 24 hours later.
• Hydration and diet: Drinking plenty of fluids after the infusion helps the kidneys process any medicine that was given. Your care team will advise on any specific dietary considerations.
• Ongoing infusions: Many patients need IV therapy as a course — for example, daily antibiotics for a week or monthly chemotherapy cycles. Your doctor will outline the full schedule and explain what to watch for between sessions.
• Follow-up: Blood tests are often repeated after a course of IV therapy to confirm that electrolyte levels have returned to normal, that an infection has cleared, or that the body has responded as expected to treatment.
• Warning signs to report promptly: fever, chills, increasing pain or swelling at the cannula site, shortness of breath (difficulty breathing), a rash, or unusual tiredness that is getting worse rather than better.