General Anesthesia

Medically Reviewed by Zilpah Sheikh, MD on March 26, 2024
8 min read

General anesthesia is medicine you get before surgeries that require you to be in a deep sleep-like state. It is given in stages – just before the surgery begins and then throughout the surgery to keep you in that sleep state. When you are in this state, you can’t feel what the surgeon is doing. This deep sleep is usually used if you have a major surgery but might be used for other purposes. For example, children who are unable to lay still for long periods or cooperate during an involved dental procedure may need a general anesthetic.

General anesthesia is given by an anesthesiologist -- a doctor who specializes in anesthesiology -- or a certified nurse anesthetist. They remain in the operating room with you throughout the surgical procedure to make sure you stay in the sleep state and to give you medication to reverse the anesthetic when the procedure is over.

General anesthesia vs. regional anesthesia

General anesthesia puts your whole body in a deep sleep-like state while regional anesthesia numbs only a specific part of the body, like from the waist down. Although you are not asleep as with a general anesthetic, typically the doctor will give you a medication that relaxes you while you have a regional anesthetic.  

You might receive regional anesthesia if you are:

General anesthesia vs. local anesthesia

Although regional anesthesia affects only certain parts of the body, it is not the same thing as local anesthesia. Local anesthesia is even more targeted. For example, your dentist injects a local anesthetic into your gum before filling or pulling a tooth, and a doctor may inject a local anesthetic around a deep cut before stitching it up. 

General anesthesia vs. sedation

Sedation is a way to help you relax enough so your doctor can perform certain procedures without them being too uncomfortable. Sedation is often used for colonoscopies and some types of biopsies. You may fall asleep once get the sedative, or you might stay awake but be in a very relaxed state.  

General anesthesia works by interrupting nerve signals in your brain and body. It prevents your brain from processing pain and from remembering what happened during your surgery.

Before your surgery, you'll get anesthesia through an IV line that goes into a vein in your arm or hand. You might also breathe in gas through a mask. You should fall asleep within a couple of minutes.

Once you're asleep, the doctor might put a tube through your mouth into your windpipe. This tube ensures that you get enough oxygen during surgery. The doctor will first give you medicine to relax the muscles in your throat. You won't feel anything when the tube is inserted.

During surgery, the anesthesia team will check these and other body functions:

Your medical team will use these measurements to adjust your medications or give you more fluids or blood if you need them. They will also make sure you stay asleep and pain-free for the whole procedure.

After surgery, the doctor will stop your anesthesia medicines. You'll go to a recovery room, where you'll slowly wake up. The doctors and nurses will make sure you aren’t in pain and that you don't have any problems from the surgery or the anesthesia.

Medications for general anesthesia are given by intravenous (IV) and inhalation (breathed in). Typically, you'll get both at the same time.

The most common IV drugs used for general anesthesia are:

  • Etomidate, which is a very short-acting medication given to induce general anesthesia. It doesn't keep you asleep.
  • Ketamine, whichcan be used alone for anesthesia, especially for quick procedures. It is also available in other forms for pain relief, sedation, and more.
  • Propofol, whichis given for anesthesia but is also a sedative. It brings on the deep-sleep state and also keeps you there.

You will likely get other IV drugs along with etomidate, ketamine, or propofol so they work better or longer. Some of the most common medications are opioids, lidocaine, and midazolam.

Inhaled medications for general anesthesia include:

  • Desflurane, whichis used for anesthesia to induce it or keep it going throughout the procedure.
  • Halothane, which is not used much anymore because it can cause several side effects.
  • Isoflurane, another inhaled medication for anesthesia but not often used because of its particularly strong odor.
  • Nitrous oxide, often called laughing gas, which is the least strong of the inhaled medications used for anesthesia. Because it doesn’t put you into a deep sleep state, it can’t be used alone and is used along with other, more powerful medications.
  • Sevoflurane, whichis also used for anesthesia, for both inducing it and maintaining it.

Before they had machines to track your vital signs during general anesthesia, doctors came up with a monitoring system to keep patients safe. They divided the system into four stages:

Stage 1: Induction. The earliest stage lasts from when you first take the medication until you go to sleep. You’re calm but able to talk for a while. Your breathing is slow but regular, and you lose the ability to feel pain.

Stage 2: Excitement or delirium. The second stage can be dangerous, so the anesthesiologist will want to get you through it as quickly as possible. You can have uncontrolled movements, fast heartbeat, and irregular breathing. You might vomit, which could make you choke or stop breathing.

Stage 3: Surgical anesthesia. At this stage, surgery can take place. Your eyes stop moving, your muscles completely relax, and you may stop breathing without the help of machines. The anesthesiologist will keep you at this stage until the procedure is over.

Stage 4: Overdose. If you get too much anesthesia, your brain will stop telling your heart and lungs to work. It’s rare with modern technology, but it can be fatal.

The doctor might give you general anesthesia if your procedure:

  • Takes a few hours or more
  • Affects your breathing
  • Affects a large area of your body
  • Involves a major organ, like your heart or brain
  • Could make you lose a lot of blood

You'll meet with your doctor and anesthesiologist before the surgery. They'll go over your surgery so you know what to expect. The anesthesiologist will ask you:

  • What medical conditions you have
  • Which medications you take, including over-the-counter medicines and herbal supplements
  • If you have any allergies, such as to eggs, soy, or any medications
  • If you smoke, drink alcohol, or take street drugs like cocaine or marijuana
  • If you've ever had a reaction to anesthesia during a past surgery

The doctor will tell you not to eat or drink anything but water for about 8 hours before your surgery. This is because general anesthesia relaxes your muscles, which can cause food from your stomach to get into your lungs.

You might need to stop taking certain medicines a week or more before your surgery. These include medications and herbal supplements that can make you bleed, such as:

Ask your doctor which medicines you can still take with a small sip of water on the morning of your surgery.

You might feel a little drowsy when you wake up from the anesthesia. Other common side effects from the medicine are:

It’s rare, but some people are confused for a few days after their surgery. This is called delirium. It usually goes away after about a week.

Some people have memory trouble after they get general anesthesia. This is more common in people with heart disease, lung disease, Alzheimer's, or Parkinson's disease. The doctor should tell you about all of these possible complications before your surgery.

General anesthesia is safe for most healthy people. Yet it can carry a greater chance of complications if you:

  • Have obesity
  • Are elderly
  • Have high blood pressure, diabetes, heart disease, lung disease, epilepsy, or kidney disease
  • Have obstructive sleep apnea, which causes your breathing to pause many times while you sleep
  • Smoke
  • Take medicines such as aspirin, which can make you bleed more
  • Are allergic to the medicines used in general anesthesia

It’s rare, but you can still be awake after you get general anesthesia. It’s even more unlikely, but you can feel pain during the surgery and not be able to move or tell the doctor you’re awake and in pain. Being awake during surgery can cause long-term emotional problems.

Anesthesia and alcohol

Drinking alcohol regularly, meaning two or more drinks per day, can increase your risk of anesthesia-related complications, so it’s important to speak with your doctor about how much alcohol you drink. Alcohol can affect:

  • The amount of anesthesia or medications you need. You may need doses, depending on the drugs, for them to work properly.
  • How long it takes for you to recover from the surgery.
  • How long it takes for your surgical wound to heal.
  • Your risk for getting an infection. You could be at higher risk for a wound infection, as well as pneumonia or a urinary tract infection, which could all lead to sepsis.
  • How easily you bleed after the surgery -- you could need a blood transfusion.

When someone is pregnant, any medical procedure can have an effect on the baby, so doctors try to avoid surgical procedures during pregnancy. About one in 50 people who are pregnant will need surgery.

Anesthesia doses have to be adapted. Pregnancy can make you more sensitive to the drugs, so you may need lower doses. Surgeons try to make sure all surgeries are done as quickly as possible to limit the amount of time their patients are under general anesthesia, but this is especially important when operating on someone who is pregnant. Shorter procedures that use general anesthesia for less than 3 hours are preferred. 

Whenever possible, surgeons use regional anesthesia when performing surgical procedures. But if you need a major surgery and a regional anesthetic isn’t possible, you will need general anesthesia. Surgery with general anesthesia is relatively safe, although there are possible complications, especially for people who have risk factors, like those who smoke or have chronic illnesses like diabetes or high blood pressure. Speak with your doctor about any concerns you may have if you are going to have general anesthesia.

How long does it take to recover after general anesthesia?

After the surgery, the anesthesiologist or certified nurse anesthetist will reverse the general anesthesia so you are no longer in the deep-sleep state. You may continue to sleep, but it’s a lighter sleep, until you wake up completely. It can take a few hours to feel completely oriented again. General anesthesia drugs can stay in your system for up to 24 hours, so it’s important not to drive or do anything that requires your full attention during that time.

When is general anesthesia not needed?

You may not need general anesthesia if your surgeon can do the procedure using a regional anesthesia or a local one, depending on the procedure.