Decongestants: What Thyroid Patients Need to Know

Certain cold and flu drugs can pose risks if you have thyroid disease

Young woman blowing her nose in the handkerchief. Shallow depth of field used. The background has a light gray vertical pattern.
KirbusEdvard/E+/Getty Images

There's no cure for the common cold or for its more serious sister illness, seasonal flu. But there are plenty of over-the-counter (OTC) medications for treating the nasal congestion that's a major symptom of these viral illnesses. Most decongestants are safe and effective for the majority of folks who take them, but for those with an overactive thyroid (hyperthyroidism) or an underactive thyroid (hypothyroidism), some can do more harm than good.

Decongestants and Heart Health

Several types of decongestants work by causing the blood vessels in the linings of the nasal passages to contract and narrow. This decreases blood flow to the lining of the nose and sinuses, thereby reducing congestion and the production of mucus.

The catch is, this effect isn't limited to nasal passages: Blood vessels throughout the body are affected, which can be dangerous for someone with a thyroid condition. That's because both hyperthyroidism and hypothyroidism can affect the heart and circulatory system.

Pseudoephedrine can strain an already overtaxed heart or further increase high blood pressure, worsening two common issues related to hyperthyroidism. 

The decongestant most likely to be problematic is pseudoephedrine, which is sold not only as a single-ingredient medication, but is found in multi-symptom cold, flu, and allergy remedies as well. (Note that because pseudoephedrine has been used illegally to make methamphetamine, it is sold from behind the pharmacy counter.)

Less potentially problematic, but still important to be aware of, is phenylephrine.

These decongestants show up in many products, and some brands have products that contain both ingredients; it's important to read labels so that you know what you're taking.

These lists represent a small sample of the many OTC medications that have pseudoephedrine or phenylephrine alone or in combination with other ingredients.

Common Medications With Psuedoephedrine

  • Advil Cold and Sinus

  • Alavert Allergy and Sinus D-12

  • Aleve-D Sinus and Cold

  • Allegra-D

  • Claritin-D

  • Mucinex D

  • Sudafed 12/24 Hour

  • Sudafed Congestion

  • Theraflu Max-D Severe Cold and Flu

  • Tylenol Sinus Severe Congestion Daytime

Common Medications With Phenylephrine

  • Actifed Cold and Allergy

  • Advil Congestion Relief

  • Alka-Seltzer Plus

  • Benedryl-D Allergy Plus Sinus

  • Excedrin Sinus Headache

  • Robitussin Cough and Cold CF

  • Sudafed PE

  • Theraflu

  • Triaminic

  • Tylenol Allergy Multisymptom

  • Vicks DayQuil

Phenylephrine is also the active ingredient in nasal sprays for treating decongestion. Although the drug is targeted to blood vessels in the lining of the nose, experts don't know for sure that it won't affect vessels throughout the body, so you should check with your doctor before using a nasal spray (such as Neosynephrine) if you have hyperthyroidism.

The same may be true for nasal sprays containing oxymetazoline. These include:

  • Afrin
  • Anefin
  • Dristan
  • Mucinex
  • Nostrilla
  • Vicks Sinex
  • Zicam

Interactions With Thyroid Medications

Hypothyroidism is managed with a synthetic form of thyroxine (T4) called levothyroxine, available under the brand names Synthroid or Levothroid.

People may be at increased risk of cardiovascular side effects if they take pseudoephedrine or phenylephrine and levothyroxine. This could be especially dangerous for someone who has preexisting heart disease.

An Overview of Levothyroxine

Regardless of the type of thyroid disorder you have, whether you take medication to treat it, or happen to have a heart condition as well, it's best to err on the side of caution before taking a decongestant for a cold or flu and speak with your doctor.

Alternatives to Decongestants

Of course, there are things you can do to relieve nasal congestion from a cold or flu without medication:

  • Try a nasal dilator that widens nasal passages, such as Breathe Right strips.
  • Rinse your sinuses with a sterile saline solution (using a neti pot).
  • Use a saline spray or drops to thin mucus and make it easier to expel when you blow your nose.
  • Run a humidifier in the room where you spend the most time.
  • Take a warm shower or sit in the bathroom with the shower running hot enough to steam up the room.

If none of these strategies work and you're too miserably congested to let your cold run its course, check with your doctor to find out if there are other ways to get relief.

Was this page helpful?
Article Sources