Last Updated on November 27, 2025 by Bilal Hasdemir

Every year, over 1.5 million PET scans are done in the United States. They help doctors diagnose and manage health issues, like cancer. A PET scan uses advanced imaging to look at how the body works. But, it’s important to get ready right before the scan to get good results.

Getting ready for a PET scan is very important. Some foods and activities can mess up the scan’s results. This might lead to wrong diagnoses or more tests. Knowing what to avoid before a PET scan is key for both patients and doctors.

Key Takeaways

• Avoid sugary foods and drinks before a PET scan.
• Some medicines might need to be stopped or changed before the scan.
• Tell your doctor about any recent health issues or procedures.
• Follow the diet advice given by your healthcare team.
• Good preparation is essential for accurate scan results.

Understanding PET Radiology Scans and Their Purpose

PET scans have changed how we diagnose diseases. They give detailed info on how our body works. This tech is key in finding and treating many health issues.

What is a PET Scan and How Does It Work?

A PET scan, or Positron Emission Tomography scan, shows how our body’s parts work. It uses a special drug that lights up on the scan. This drug is absorbed by our body’s tissues and organs.

The scan starts with a small dose of radioactive drug. The most common one is Fluorodeoxyglucose (FDG). It’s a sugar molecule with a radioactive tag. As it spreads through our body, the PET scanner picks up the signals. This creates detailed images of our body’s inner workings.

Common Medical Conditions Diagnosed with PET Scans

PET scans are used for many health issues. They help find and track diseases. Here are some examples:

• Cancer diagnosis and staging
• Monitoring the effectiveness of cancer treatment
• Diagnosing neurological disorders such as Alzheimer’s disease
• Assessing heart disease and viability of heart tissue

These scans give doctors a clear view of how our body’s tissues work. This helps them spot diseases early and accurately.

Differences Between PET, CT, and MRI Scans

PET scans look at how our body’s tissues work. But CT and MRI scans show different things. Knowing what each scan does helps doctors choose the right one for each patient.

A CT scan uses X-rays to show our body’s inside. It’s great for seeing bones, soft tissues, and blood vessels. An MRI scan uses magnets and radio waves to show our body’s inside without X-rays or radioactive tracers.

A PET scan is special because it shows how our body’s tissues work. Often, it’s used with CT scans (PET/CT). This way, doctors get both functional and anatomical info at once.

Why Proper Preparation is Critical for Accurate Results

To get reliable results from a PET scan, you must prepare well. This preparation is key to getting accurate and trustworthy scan results.

How Preparation Affects Image Quality

The quality of PET scan images depends a lot on how well you prepare. Eating certain foods or drinks before the scan can change how your body works. This can lead to results that are not accurate.

For example, eating too much sugar can mess with how your body uses glucose. This is important because PET scans use a glucose tracer. So, preparing right helps make sure the images are clear and true. This lets doctors make better decisions.

Consequences of Improper Preparation

Not preparing well for a PET scan can cause big problems. Results that are not accurate can mean you might get a wrong diagnosis. This can lead to more tests and stress.

In some cases, you might have to do the scan again. This means more radiation and higher costs for healthcare.

Patient Responsibility in the Preparation Process

Patients have a big part to play in getting ready for a PET scan. It’s important to follow the instructions from your healthcare team. This includes what to eat, how long to fast, and managing your meds.

By being active in your preparation, you help make sure your scan results are right. This helps doctors diagnose and plan treatment better.

Dietary Restrictions: Foods to Avoid Before Your PET Scan

To get the best results from your PET scan, it’s important to follow certain dietary rules. What you eat before the scan can greatly affect the quality of the images. So, it’s key to know what to eat and what to avoid.

High-Carbohydrate Foods to Eliminate

High-carb foods can mess up your PET scan results, which is a big deal for cancer scans. You should avoid or cut down on:

• Bread and baked goods
• Pasta and rice
• Sugary snacks and desserts
• Fruit juices and sweetened drinks

These foods can change your blood sugar levels. This can mess with how the radiotracer works in the PET scan.

Sugar and Glucose Considerations

It’s very important to watch your sugar and glucose intake before a PET scan. Eating too much sugar can cause:

1. High glucose levels, which might mess with the radiotracer’s uptake.
2. Poorer image quality because of the competition between glucose and the radiotracer.

Try to avoid sugary foods and drinks for at least 24 hours before your scan.

Recommended Low-Carb Options for Pre-Scan Meals

Choosing low-carb meals can help make sure your PET scan results are right. Good options include:

• Lean proteins like chicken, fish, and tofu
• Vegetables like broccoli, spinach, and bell peppers
• Nuts and seeds, in small amounts

These foods are low in carbs and full of nutrients. They help keep you healthy while you prepare for your scan.

By sticking to these dietary tips, you can help make sure your PET scan results are accurate. This gives your healthcare team the info they need to care for you well.

Fasting Requirements: Timing and Exceptions

Knowing the fasting requirements before a PET scan is key for good results. Fasting is important to get clear and reliable scan images.

Standard Fasting Guidelines for Different Types of PET Scans

The standard fasting guidelines change based on the PET scan type. Usually, patients must fast for a few hours before the scan. This ensures the images aren’t mixed up by recent food.

For most PET scans, fasting for 4 to 6 hours is recommended. But, some scans might need longer fasting. Always follow your healthcare provider’s specific instructions.

Medical Exceptions to Fasting Rules

There are medical exceptions to fasting rules. Some medical conditions, like diabetes, need special fasting plans.

If you have such a condition, tell your healthcare provider. They will guide you on how to prepare for the PET scan.

Water Consumption During the Fasting Period

Many wonder if they can drink water before a PET scan. Usually, drinking water is okay during fasting. It helps with the radiotracer’s distribution.

But, avoid flavored or sweetened water. Also, listen to your healthcare provider’s advice on fluids.

In short, following the pet scan fasting requirements is essential. By sticking to the guidelines and sharing any health concerns, patients can get accurate PET scan results.

Beverages to Avoid: Caffeine, Alcohol, and Sugary Drinks

Before a PET scan, it’s important to choose your drinks wisely. Some drinks can change how your body works, which might mess up the scan’s results.

Effects of Caffeine on PET Scan Results

Caffeine can speed up your heart rate and blood pressure. Drinking it before a PET scan might mess up the scan’s accuracy. It’s best to skip caffeinated drinks like coffee, tea, and energy drinks for 24 hours before your scan.

Key beverages to avoid:

• Coffee
• Tea (both black and green)
• Energy drinks
• Certain sodas

Alcohol Consumption Guidelines

Alcohol can also mess with your PET scan results. It can change how your body works and might react with the scan’s chemicals. It’s usually best to not drink alcohol for 24 hours before your scan. But, the exact time might depend on your scan type and health.

Always check with your doctor about drinking alcohol before your PET scan.

Hidden Sources of Sugar in Beverages

Many drinks have hidden sugars that can raise your blood sugar. This can change how the scan works. Sugary drinks can make your blood sugar go up, which might mess with the scan’s results.

Common sugary beverages to limit or avoid:

1. Sugary sodas
2. Fruit juices with added sugars
3. Sweetened teas and coffee drinks
4. Energy drinks

Knowing and avoiding these drinks can help make your PET scan results more accurate. Always listen to your healthcare team’s advice on what to eat and drink before your scan.

Medications and Supplements That Can Interfere With PET Scan Results

Before you get a PET scan, it’s important to know which medicines and supplements might mess up the results. PET scans use a special tracer that shows up on the scan. But, some things you take can change how this tracer works, making the scan not show what it should.

Common Prescription Medications to Avoid

Some medicines you take by prescription can mess with PET scan results. For example, metformin, a diabetes drug, can change how the tracer is taken up. Always tell your doctor about any medicines you’re on.

• Diabetes medications (e.g., metformin)
• Certain antidepressants
• Some blood pressure medications

Over-the-Counter Medications That Affect Results

OTC medicines can also mess with PET scan results. For instance, cold medications and pain relievers with pseudoephedrine or acetaminophen can change the scan’s accuracy.

• Cold medications
• Pain relievers (e.g., acetaminophen)
• Antihistamines

Herbal Supplements and Vitamins to Discontinue

Herbal supplements and vitamins can also mess with PET scan results. Big doses of ginseng and vitamin C can change how the tracer is taken up.

• Ginseng
• High-dose vitamin C
• Other herbal supplements

Talking to your doctor about all medicines, supplements, and vitamins before your PET scan is key. This helps make sure your scan shows the right information.

Physical Activity Limitations Before Your PET Radiology Scan

Knowing how physical activity affects PET scan prep is key. It can change how the radiotracer spreads in your body. This might affect the scan’s accuracy.

Why Exercise Should Be Limited

Exercise can change blood flow and how your body uses glucose. This can alter the radiotracer’s uptake in tissues. This might lead to unclear scan images or the need for more scans.

Limiting strenuous exercise before a PET scan is recommended. Talk to your healthcare provider about your exercise routine. They can guide you on what’s best for your situation.

Recommended Activity Levels 24-48 Hours Before

In the 24 to 48 hours before your PET scan, stick to your usual daily activities. But, avoid strenuous exercise or unusual physical exertion. This keeps your body’s state stable, improving the scan’s accuracy.

• Light walking is usually acceptable and can be continued as normal.
• Avoid intense workouts, such as running or weightlifting.
• Refrain from starting any new exercise regimen in the days leading up to the scan.

Activities That Are Safe vs. Those to Avoid

It’s important to know which activities are safe and which might affect your scan. Everyday light activities are usually okay. But, some actions should be avoided to prevent scan outcome issues.

Activities to avoid include:

• Strenuous exercise, as mentioned, due to its impact on glucose metabolism and blood flow.
• Consuming large or high-glucose meals that could affect blood sugar levels.

On the other hand, safe activities include:

• Light housekeeping or normal household chores.
• Short walks or gentle stretching exercises.
• Engaging in hobbies that do not involve strenuous physical activity.

By following these guidelines, patients can help ensure their PET scan results are accurate. This aids in better diagnosis and treatment planning.

Clothing and Accessories Guidelines for Scan Day

On the day of your PET scan, it’s important to wear the right clothes. Avoid certain accessories to make sure the procedure goes well.

Metal Objects and Jewelry Restrictions

Metal objects can mess with the PET scan imaging. It’s best to not wear jewelry, mainly anything with metal. This is because it can cause problems on the scan images.

• Remove all jewelry, including necklaces, earrings, and rings.
• Avoid clothing with metal parts like zippers, buckles, or buttons.
• Inform your healthcare provider if you have any metal implants or devices.

Appropriate Clothing Choices

Choose clothes that are comfy and don’t have metal parts. Pick outfits that are easy to take off if needed.

Tips for Choosing the Right Clothing:

1. Opt for clothing with elastic waistbands.
2. Select shirts or tops that can be easily lifted.
3. Wear comfortable shoes, as you may be required to walk or stand during the scan preparation.

Makeup, Lotions, and Deodorants Considerations

Some personal care products can have metals or substances that might mess with the scan. It’s best to avoid applying:

• Makeup, specially eye shadow or eyeliner that may contain metallic particles.
• Deodorants or antiperspirants that can contain metals.
• Certain lotions or creams that might leave residues on your skin.

For the best results, follow the specific instructions from your healthcare provider about personal care products on the day of your PET scan.

Special Considerations for Diabetic Patients

Diabetic patients need to be extra careful before a PET scan. They must watch their blood sugar levels, take their medicine, and make lifestyle changes. These steps are important for getting ready for the scan.

Blood Sugar Management Before a PET Scan

Keeping blood sugar levels right is key for diabetic patients before a PET scan. High or low sugar can mess up the scan’s results. Here’s what diabetic patients should do:

• Check their blood glucose often before the scan.
• Eat a balanced diet to keep blood sugar steady.
• Tell their doctor about their blood sugar and any worries.

Tips for Managing Blood Sugar:

1. Eat foods low in simple carbs and sugars.
2. Drink lots of water to stay hydrated.
3. Take your medicine as your doctor says, unless they tell you not to.

Insulin and Oral Medication Adjustments

Diabetic patients might need to change their insulin or oral meds before a PET scan. The exact change depends on their treatment and the scan’s needs.

Talking to your doctor about changing your meds is very important.

Communication Protocol With Your Healthcare Team

Talking clearly with your healthcare team is essential for diabetic patients getting a PET scan. Make sure to:

• Tell your doctor about your diabetes plan.
• Ask any questions or share any concerns about the scan prep.
• Do exactly what your healthcare team tells you to do about meds, diet, and prep.

By managing blood sugar, adjusting meds, and talking openly with your healthcare team, you can have a good PET scan experience.

Pregnancy, Breastfeeding, and Contraception Precautions

It’s important to know how PET scans affect pregnancy, breastfeeding, and birth control. PET scans use small amounts of radioactive tracers. These can be risky for a fetus or baby and might affect how the body works.

Risks and Contraindications During Pregnancy

When you’re pregnant, getting a PET scan is a big deal. The main worry is the radiation’s effect on the fetus. Doctors say to avoid PET scans unless really needed and look for other ways to diagnose.

If a PET scan is needed, doctors try to use the least amount of radioactive tracer. This helps protect the fetus. Pregnant women or those who might be should tell their doctor before a PET scan.

Breastfeeding Guidelines After Radiotracer Exposure

For moms who are breastfeeding, there’s a worry about the radiotracer in PET scans getting into the baby’s milk. Usually, moms shouldn’t breastfeed right after a PET scan until the tracer is gone. How long to wait depends on the tracer used.

Guidelines say to wait at least 24 hours before breastfeeding again. It’s key for moms to talk to their doctor about breastfeeding plans before the scan.

Birth Control Considerations and Timing

Birth control and PET scans also need some thought. Most birth control, like hormonal types, doesn’t mess with PET scan results. But, it’s smart to tell your doctor about any meds or supplements.

When to have a PET scan, like during your period or with birth control, isn’t usually a big deal unless your doctor says so. But, it’s good to ask your doctor about any worries or questions.

In short, PET scans are useful but need careful thought when you’re pregnant, breastfeeding, or on birth control. It’s best to talk to your doctor to make sure you’re safe.

Contrast Agents and Allergy Considerations

To have a safe and effective PET scan, it’s key to know about contrast agents and allergies. Contrast agents help make medical images clearer. This makes it easier to spot and track health issues.

Types of Contrast Used in PET Scans

Different contrast agents are used in medical imaging, including PET scans. The most common are iodine-based and barium-based. But PET scans usually use a radioactive tracer like Fluorodeoxyglucose (FDG). This is not a traditional contrast agent. Yet, some PET scans might also use iodine-based contrast with CT scans.

Common Allergic Reactions and Symptoms

Allergic reactions to contrast agents can vary. They can be mild or severe. Symptoms include:

• Itching or hives
• Nausea or vomiting
• Sneezing or coughing
• More severe reactions can involve difficulty breathing or a rapid heartbeat

It’s important for patients to know these symptoms. They should tell their healthcare providers about any allergies.

Disclosing Your Allergy History Before the Scan

Before a PET scan, patients must share their medical history. This includes any allergies to contrast agents or other substances. This info helps doctors prepare and reduce risks. Patients should be ready to talk about:

• Any previous reactions to contrast agents
• Known allergies to iodine or other substances
• Any other medical conditions that could affect the scan

Being informed and open helps ensure a safe and successful PET scan.

The Day Before Your PET Scan: A Complete Checklist

To get the best results from your PET scan, follow a specific plan the day before. This preparation is key to getting accurate results and a correct diagnosis.

24-Hour Preparation Timeline

The 24 hours before your PET scan are very important. Here’s a guide to help you:

• 24 hours before: Start fasting, unless your doctor tells you not to.
• 12 hours before: Don’t eat sugary foods or drinks.
• 6 hours before: Don’t drink water, unless your doctor says it’s okay.

Sticking to this timeline helps avoid problems during your scan.

Common Mistakes to Avoid

Some common mistakes can affect your PET scan’s quality. Watch out for these:

1. Don’t eat foods high in sugar or carbs close to your scan time.
2. Make sure to tell your doctor about all your medications and supplements.
3. Avoid hard exercise near your scan time.

Steering clear of these mistakes ensures a precise and smooth scan.

Questions to Ask Your Healthcare Provider

It’s important to clear up any doubts with your doctor. Ask these questions:

• What specific foods should I avoid eating?
• Are there any medicines or supplements I should skip?
• What happens if I don’t follow the prep instructions?

Talking openly with your doctor helps ease worries and makes sure you’re ready.

The Morning of Your PET Scan: Last-Minute Don’ts

The morning of your PET scan is very important. You need to plan carefully and follow certain guidelines. Knowing what to avoid can help get the best results from your scan.

Morning Medication Guidelines

On the day of your PET scan, it’s key to follow medication rules. Check with your doctor about any medicines you’re taking. Some might need to be changed or stopped. For example, diabetes medicines might need special care.

Make sure to:

• Tell your doctor about all your medicines, including over-the-counter ones.
• Follow the exact instructions about when and how much to take.
• Ask any questions or share any worries you have about your medicines.

Transportation and Accompaniment Requirements

Getting to and from the PET scan place is important. Think about getting someone to come with you. You might feel tired or uncomfortable after it’s done. Also:

1. Make sure you have a way to get there, like a friend driving you.
2. See if the place offers any help with getting there.
3. Bring someone who can help and support you.

Documentation and Insurance Information to Bring

It’s important to bring the right papers and 

info. Get these things ready:

• Your ID and cards.
• Any medical records or scan results from before.
• A list of your medicines and how much you take.
• Your doctor’s note or prescription for the scan.

Being ready and knowing what to avoid can make your PET scan go well.

Post-Scan Precautions and Activities to Avoid

After your PET scan, it’s important to follow certain precautions. This is for your safety and the safety of others. The PET scan uses a special tracer that will leave your body over time. But, there are steps you should take to avoid any risks.

Radiation Safety Guidelines After Your Scan

It’s key to follow radiation safety rules after your PET scan. The tracer emits radiation that can be detected by others. To keep exposure low:

• Drink lots of water to help get rid of the tracer.
• Stay away from pregnant women and kids for at least 24 hours.
• Keep a safe distance from others, like in crowded places.

Interactions With Children and Pregnant Women

When around kids and pregnant women after your scan, be extra careful. The radiation from the tracer can harm them more. To protect them:

1. Don’t hug or hold them for at least 24 hours.
2. Don’t share food or drinks, as it might pass on the tracer.
3. Wash your hands often to stay clean.

When You Can Resume Normal Activities

You can usually go back to your normal life soon after a PET scan. But, always listen to what your doctor says. Usually, you can get back to your routine in a day or two. But, some activities might need to wait or be done differently for your safety.

Key Takeaways: After your PET scan, follow the guidelines to reduce radiation exposure to others. This is important for kids and pregnant women. By following these steps, you can ensure a safe recovery for everyone.

Conclusion: Ensuring the Best Possible PET Scan Experience

Getting ready for a PET scan is very important. By knowing what to do and following the steps, you can get accurate results. This makes the scanning process smoother.

Preparing for a PET scan is not just about showing up. It involves planning ahead. This includes following dietary rules, avoiding certain medicines, and not being too active. These steps help get clear images for a correct diagnosis.

Being well-prepared is key to a good PET scan. Understanding the need for preparation and taking the right steps helps your healthcare team. Always follow the guidelines and ask questions if you’re unsure about anything.

FAQ

What is a PET scan and how does it work?

A PET (Positron Emission Tomography) scan is a medical test. It uses a tiny amount of radioactive material. This material is injected into the body and absorbed by cells.

The cells then emit positrons. These positrons are caught by the PET scanner. This helps doctors diagnose and treat health issues.

What should I avoid eating before a PET scan?

Avoid foods high in carbs and sugar before a PET scan. Instead, eat low-carb meals. Your healthcare provider will give you specific dietary advice.

Do I need to fast before a PET scan?

Yes, fasting is usually needed before a PET scan. The fasting time varies. It’s usually 4-6 hours.

Can I drink water before a PET scan?

Yes, drinking water is okay before a PET scan. But, always follow your healthcare provider’s fluid intake guidelines.

Are there any medications I should avoid before a PET scan?

Some medications, like those with sugar or certain herbal supplements, can affect PET scan results. Tell your healthcare provider about all medications and supplements you’re taking.

Can I exercise before a PET scan?

It’s best to avoid strenuous exercise 24-48 hours before a PET scan. This can impact the scan results. Talk to your healthcare provider about safe activity levels.

What should I wear on the day of the PET scan?

Wear comfortable, loose clothes and avoid metal items. You might need to change into a hospital gown during the scan.

Are there any special considerations for diabetic patients undergoing a PET scan?

Yes, diabetic patients need to manage their blood sugar before a PET scan. Inform your healthcare provider about your diabetes medication. They will guide you on adjusting your medication and managing your blood sugar.

Is it safe to undergo a PET scan during pregnancy or breastfeeding?

PET scans involve radiation, which can be risky during pregnancy. Breastfeeding women might need to stop breastfeeding after the scan. Talk to your healthcare provider about the risks and benefits.

What are the post-scan precautions and activities to avoid?

After a PET scan, follow your healthcare provider’s radiation safety guidelines. Avoid close contact with children and pregnant women for a while. You can usually go back to normal activities soon after.

How long does a PET scan take?

A PET scan’s duration varies. It depends on the scan type and body area. It can take from 30 minutes to several hours.

What should I bring to the PET scan appointment?

Bring any needed documents, info, and a list of your medications. Your healthcare provider will give you specific instructions on what to bring.