Sniffling, sneezing, coughing, aching, stuffy head andfever are more than just the list of common cold symptomsrattled off in every NyQuil commercial. They’re also often the start of many serious ailments. If you’ve been suffering from them without improvement, consider these signs you may need to put down the cold medicine and see a medical professional STAT.

1. You have a high fever.

Running a fever while you’re fighting a cold is pretty common. Most of the bacteria and viruses that cause colds multiply best at 98.6°F, so raising your temperature is one of your body’s best defenses against them. However, if you’re an adult with a fever higher than 102°F, it could be a sign that the invader your body is working against is a serious one.

2. You got sick, got better, but then got sick again.

Rebound illnesses can be signs of superinfections—serious secondary infections that take hold when your immune system has been weakened by the common cold or flu. A trip to see the doctor can ensure there’s nothing dangerous going on.

3. You have a severe headache.

We’re not talking sinus pain associated with congestion or a tension headache after a long day at work, but continuous head pain so intense it affects your ability to think clearly or even function. It could indicate your central nervous system has been compromised by a bacteria or virus. Known as meningitis, early symptoms of such an infection often mimic the flu.

4. You’re too weak to get out of bed.

Muscle aches and extreme fatigue often accompany the flu. Though flu is caused by a virus, and antibiotics will not make it go away, your doctor may be able to prescribe an antiviral medication that will shorten the duration of your symptoms and prevent your flu from causing secondary infections.

5. You have a chronic health condition.

While most healthy adults can survive a cold otherwise unscathed, those with serious conditions—such as kidney disorders, heart problems or diabetes—should see their doctor anyways. He or she can help you prevent your cold from causing any potentially dangerous complications.

6. Your heartbeat feels irregular.

Arrhythmia is a problem with your heartbeat. It may feel as though it is beating too quickly, too slowly, or occasionally missing a beat. This may cause a fluttering feeling, dizziness or even fainting. Minor, brief arrhythmias are generally not life threatening. However, when accompanied by cold symptoms, they may indicate you are becoming severely dehydrated or a virus is attacking your heart.