Side Effects Of a Nuclear Scan | What To Expect After

A nuclear scan uses a small amount of radioactive tracer to show how an organ works. Many people feel nothing from the tracer and go home the same way they arrived. Still, it’s normal to want a straight answer about what you might feel after you leave the imaging center.

This article lists common post-scan sensations, less common reactions, and the moments that call for a phone call.

What A Nuclear Scan Measures

The tracer is linked to a compound your body takes up in a target tissue. A camera detects the tracer and builds images that reflect activity or blood flow.

Tracers leave through urine, stool, or breath over hours to days. Teams pick the lowest dose that still answers the medical question.

Side Effects Of a Nuclear Scan And When To Call

Many patients notice no change at all. When symptoms show up, they often fade fast.

IV-Site Soreness And Bruising

A quick pinch, a dull ache, or a bruise near the injection spot is common. Some people get mild redness from tape.

What Helps At Home

Leave the bandage on for an hour or two, then let the skin breathe. A cold pack can ease tenderness.

Nausea, Headache, And Lightheadedness

Queasiness or a mild headache is often tied to fasting or dehydration. Once staff says you can eat, a light snack and water can help.

Temporary Symptoms During A Heart Stress Test

If your scan includes exercise or a stress medicine, you may feel flushed or short of breath during that portion. Staff watches you closely, and symptoms usually fade within minutes.

Rash Or Allergy-Like Signs

Reactions to radiotracers are uncommon, yet it’s smart to know the warning signs. Hives, widespread itching, swelling of lips or eyelids, wheezing, throat tightness, or fainting call for urgent care.

When To Seek Emergency Care

Call your local emergency number right away for breathing trouble, face swelling, fainting, or chest pain that keeps building. For fever, spreading redness, or nonstop vomiting, call your clinician’s office the same day.

Why Side Effects Differ By Scan Type

“Nuclear scan” is a broad label. Side effects vary by tracer and by the prep rules, plus any stress medicine used.

Bone Scans

Bone scans usually involve an injection, a waiting period, then pictures. Most people feel nothing from the tracer. The main challenge is time and staying still on the table.

Thyroid Studies

Some thyroid tests use a pill or liquid tracer. Stomach upset can happen, though many people notice nothing. If you take thyroid medicine, ask the ordering office about timing, since doses can affect uptake measurements.

PET Scans

PET scans often come with fasting rules and blood sugar checks. Hunger can cause headache, shakiness, or irritability. If you have diabetes, tell the imaging center early so your meal and insulin plan fits the test window.

Radiation And Day-Of Safety Steps

Diagnostic nuclear scans use low-dose radiation. Two habits can help move tracer out: drink fluids as allowed and use the restroom when you need to.

For a clear overview of how nuclear medicine exams work and what safety checks are built in, see RadiologyInfo’s general nuclear medicine page. For radiation protection principles used across medical imaging, including nuclear medicine, the FDA’s medical imaging radiation safety white paper explains the core approach.

Most people can be around others after the scan. Some tracers come with short-term spacing steps around infants or pregnant household members, and the imaging team will give written instructions.

If your tracer leaves through urine, the center may ask you to drink extra water and empty your bladder often for the rest of the day. If you share a bathroom, flush twice when told, wipe any splashes, and wash hands well. Keep the tracer off towels and away from kids and pets.

If you care for an infant, ask about a short spacing window. It often means skipping long lap time and face-to-face snuggles, not avoiding the same room. A normal car ride home is fine unless you are given a spacing sheet. Follow the written steps you leave with, then return to routine once the timer is up.

Common Effects And Typical Timing

This table matches common sensations to the time window when they tend to show up. Timing shifts by tracer and by your own metabolism.

Effect	How It Can Feel	Usual Window
IV-site soreness	Dull ache or tenderness near the needle spot	Minutes to 24 hours
Bruising	Blue-purple mark, mild swelling	Hours to 3 days
Redness from tape	Itchy patch where adhesive sat	Hours to 2 days
Nausea	Queasy stomach, low appetite	Same day
Headache	Tight or throbbing head pain	Same day
Lightheadedness	Woozy feeling when standing	Same day
Flush during stress test	Warmth, shortness of breath, chest pressure	During stress portion
Rash or hives	Itchy bumps, raised welts	Minutes to a few hours
Metallic taste	Brief odd taste if contrast is used	Minutes

If a symptom is easing, that’s reassuring. If it spreads or comes with breathing trouble, treat it as urgent.

Things To Tell The Imaging Team Before They Start

Staff asks screening questions for a reason. A few details can change which tracer is used, how you prepare, or what steps you get after the scan.

Pregnancy And Breastfeeding

If you are pregnant, might be pregnant, or are breastfeeding, say so before any tracer is given. Feeding steps depend on the tracer and dose.

The International Atomic Energy Agency publishes clinician-facing notes on pregnancy precautions in nuclear medicine: IAEA pregnancy notes. Cleveland Clinic also lists pregnancy and breastfeeding as situations where nuclear imaging plans may change: Cleveland Clinic’s nuclear medicine imaging overview.

Kidney Function And Fluid Limits

Many tracers leave through the kidneys. If you have kidney disease, fluid limits, or dialysis, ask how much you should drink after the exam.

Diabetes, Fasting, And Meal Timing

If fasting is required, plan the timing. If you use insulin or medicines that can drop blood sugar, call the ordering office ahead of time.

What To Do Before The Appointment

A bit of prep can cut down on avoidable symptoms. Try to arrive hydrated (when allowed) and ready for some waiting.

Pack For Comfort

• Photo ID and insurance card.
• A list of medicines and allergies.
• A warm layer. Scan rooms run cool.
• A small snack and water for after the scan, unless told not to.

Plan For Stillness

If you have back or neck pain, tell staff early so they can add cushions. Bring headphones or a book for the waiting time.

What To Do After The Scan

Most people can drive, eat, and return to routine right away. If you got a sedative, you’ll need a ride.

Hydrate And Use The Restroom

Drink fluids as allowed and urinate when you need to. Wash hands well after bathroom trips.

Watch The Injection Spot

Some soreness is normal. Call your clinician if you see spreading redness, feel heat that keeps building, or develop streaking up the arm.

Action Table For Common “What Now?” Moments

This table is for the hours after you get home.

Situation	What To Do	When To Act
Mild nausea after fasting	Eat a light snack, sip water, rest	Same day; call if vomiting starts
Bruise at IV site	Cold pack, avoid heavy lifting	Watch for 48 hours
Rash or hives	Urgent care if swelling or wheeze appears	Right away if breathing changes
Chest pain after stress test	Emergency services if pain grows or comes with fainting	Right away for worsening pain
Fever after the scan	Call your clinician’s office	Same day
Spreading redness at IV site	Call your clinician; mark the edge with pen	Same day
Lightheaded on standing	Sit, drink water if allowed, eat	Same day; urgent care if fainting
Pregnant or breastfeeding after tracer	Call the imaging center for tracer-specific steps	As soon as you realize

Symptoms That Can Come From The Setup

Some discomfort comes from the prep rules, not the tracer. It often fades once you’re eating, drinking, and moving again.

If you felt anxious on the table, a short walk, a drink, and steady breathing can settle your body once you’re home.

Fasting And Caffeine Gaps

Skipping food can cause headache, nausea, shakiness, or irritability. If caffeine was restricted, withdrawal can add a pounding head.

Holding Still On The Table

Staying still can strain the neck, shoulders, or low back. Tell the technologist if you cramp or your arm falls asleep.

Questions To Ask Before You Leave

If you like having a clear plan, ask these on your way out.

• When can I eat and drink again?
• Do I need any spacing steps around infants after I leave?
• Can I take my usual medicines tonight?
• Who should I call if I notice a rash at home?
• When will my ordering clinician get the report?

Printable Checklist For Scan Day

Save this list for scan day.

• Read your prep sheet the night before and set alarms for fasting times.
• Bring a medicine and allergy list.
• Wear easy sleeves for an IV and bring a warm layer.
• Bring water and a snack for after the scan, unless told not to.
• After the scan, drink fluids as allowed and use the restroom when needed.
• Check the IV spot that evening for spreading redness or heat.
• Use the action table above if a symptom pops up at home.

Most nuclear medicine tests end with a small bruise and a long day of waiting. If something feels wrong, seek medical care.