Medical infusions deliver medications, fluids, or nutrients directly into your bloodstream through a vein. They’re used when a treatment can’t be taken as a pill, when your body needs something faster than the digestive system can deliver, or when a drug would break down in your stomach before it could work. The range of conditions treated through infusions is broad, spanning infections, cancer, autoimmune diseases, neurological disorders, mental health conditions, and basic dehydration.
Infections and Antibiotics
One of the most common reasons for an infusion is an infection that oral antibiotics can’t clear. If you’ve been taking antibiotic pills and the infection isn’t responding, or if the infection is severe enough to require high concentrations of the drug in your blood quickly, IV antibiotics are the next step. Infusions are also used when you can’t swallow pills, when you need a long course of antibiotics (weeks rather than days), or when your care team wants to monitor you for an allergic reaction to a new antibiotic in a controlled setting.
Cancer Treatment
Chemotherapy is one of the most well-known uses of infusion therapy. Treatment sessions vary widely: some take just a few minutes, while others run for several hours. In certain cases, you may need a continuous infusion lasting several days, which can start in a hospital or infusion center and continue at home with a portable pump.
Beyond traditional chemotherapy, newer cancer treatments are also given as infusions. CAR T-cell therapy, for example, is used for certain lymphomas. Your immune cells are collected, genetically modified in a lab to better attack cancer, and then infused back into your body. In 2024 alone, the FDA approved several new IV cancer therapies, including treatments for small cell lung cancer, stomach cancer, and a rare bile duct cancer. An injectable imaging agent was also approved that helps surgeons identify cancerous tissue during breast cancer surgery in real time.
Autoimmune Diseases
Biologic medications are a major category of infusion therapy, and they’ve transformed treatment for autoimmune conditions like rheumatoid arthritis, Crohn’s disease, psoriasis, and ankylosing spondylitis. These drugs are large, complex molecules that would be destroyed by stomach acid and digestive enzymes if swallowed, so they must be delivered through an IV or injection.
Biologics work by targeting specific parts of your immune system that drive inflammation. Some block a protein called TNF-alpha, which fuels the inflammatory response in joints, skin, and the gut. Others deplete a type of immune cell (B cells) that produces the antibodies mistakenly attacking your own tissues. A third group targets interleukins, signaling molecules that either ramp up or dial down inflammation. The first biologic approved for autoimmune disease came in 1998 for Crohn’s disease and has since been approved for several other conditions. Today, dozens of biologics are available, and the choice depends on your specific disease and how you’ve responded to earlier treatments.
Immune System Support
Intravenous immunoglobulin, or IVIG, is a concentrated solution of antibodies collected from thousands of blood donors. It’s infused to treat people whose immune systems either don’t produce enough antibodies or are attacking their own nerves and tissues. Neurological conditions treated with IVIG include Guillain-Barré syndrome (a condition where the immune system suddenly attacks the nerves), chronic inflammatory demyelinating polyneuropathy, and multifocal motor neuropathy.
IVIG doses are calculated based on body weight, and treatment sessions are typically spaced at least four to six weeks apart. The total dose is spread over two to five days per cycle, depending on how much you need and how well you tolerate the infusion.
Hydration and Nutrition
IV fluids are the simplest form of infusion. If you’re severely dehydrated from illness, surgery, or an inability to drink enough, IV fluids restore your body’s water and electrolyte balance far faster than drinking can. For people who are chronically anemic, infusions of iron or blood products can replenish what the body isn’t making on its own.
Parenteral nutrition takes this further. When your digestive tract can’t absorb food properly, or can’t be used at all, a nutrient-rich solution containing proteins, fats, sugars, vitamins, and minerals is delivered directly into a vein. This is common in people with short bowel syndrome, bowel obstructions, or fistulas in the GI tract. It’s also used during recovery from serious illness when the gut alone can’t keep up with the body’s nutritional demands.
Mental Health and Pain
Ketamine infusion therapy has gained attention as a treatment for depression that hasn’t responded to standard medications or talk therapy. Low-dose ketamine is administered in a clinical setting under supervision, and some people notice improvement within hours. Those effects can fade within days or weeks, so repeat sessions are often needed. Before starting, you’ll go through a medical review, and you may need clearance from specialists depending on your health history. Off-label, low-dose ketamine infusions are also used for severe pain from injuries, surgery, or chronic conditions.
Alzheimer’s Disease
A newer frontier for infusion therapy is Alzheimer’s treatment. In 2024, the FDA approved an IV infusion that targets and clears amyloid plaques, the protein clumps that build up in the brains of people with Alzheimer’s. This type of therapy doesn’t cure the disease, but it aims to slow the decline in memory and thinking by removing one of its biological drivers. Eligibility is limited, and treatment requires regular monitoring with brain scans to watch for side effects like swelling or small bleeds in the brain.
Where Infusions Happen
Infusions take place in hospitals, outpatient infusion centers, doctor’s offices, and increasingly at home. The setting depends on the complexity of the treatment, how long the infusion takes, and whether you need close monitoring. Hospital and clinic infusions are typical for chemotherapy, IVIG, and first doses of biologics where reactions need to be watched for.
Home infusion is an option for many long-term treatments. To qualify under Medicare, you need to be under a physician’s care with a documented treatment plan, and the drug must be administered through a pump classified as durable medical equipment. The infusion also needs to run for at least 15 minutes. Home infusion covers a range of therapies including IV antibiotics, parenteral nutrition, and certain biologics. It doesn’t cover things like insulin pumps or medications you can give yourself without professional support.
How Infusions Are Delivered
The access point for your infusion depends on what’s being given and for how long. A standard peripheral IV, the small catheter placed in a vein in your hand or forearm, works for short-term treatments and many one-time infusions. If you need treatment over weeks or months, your care team may place a PICC line, a longer catheter threaded through a vein in your arm up to a large vein near your heart. PICC lines and similar central lines can stay in place for extended periods, reducing the need for repeated needle sticks and allowing delivery of medications that would irritate smaller veins.
What Side Effects to Expect
Most infusion reactions are mild. Chills, fever, nausea, headache, skin rash, and itching are the most common. These tend to happen during or shortly after the infusion and often improve on their own or with simple interventions like slowing the drip rate. More serious reactions can include a rapid heart rate, a drop in blood pressure, and shortness of breath, which is why many infusion centers monitor you for a period after treatment ends. The risk of a reaction is highest during the first few sessions with a new medication and generally decreases over time as your body adjusts.