The Best Cold and Flu Medicines to Take if You Have Diabetes: A Pharmacist Explains

Ah choo! 'Tis the season for sickness. If you have diabetes it's important to be aware of the ingredients in over-the-counter medications that could impact your blood sugar. Here, a pharmacist recommends good choices for you.

woman sick with fluIf you have diabetes it's important to be aware of the contents of common OTC cold remedies—some can impact your blood sugar and contribute to other problems. (Photo:123rf)

As a pharmacist, I get asked for recommendations for cough, stuffy nose, and chest congestion all the time. Most likely, these are symptoms of what is often referred to as the “common cold".

The common cold won't last forever fortunately and is often caused by a virus known as the rhinovirus. If symptoms last longer than 5-7 days or are accompanied by a high fever, a medical professional should be consulted.

As a pharmacist, it's important for me to know what other health issues a person may have as well as their current medication history to help me make a reasonable—and more importantly—safe recommendation.

During times of illness it is extremely importance to monitor blood sugars carefully and to stay well hydrated. People with diabetes are especially prone to dehydration. Drink plenty of clear fluids, and maintain carbohydrate intake of you are able. Clear fluids are the best way to stay hydrated. Dairy products such as milk thicken mucus and can increase sputum viscosity, or phlegm.

Here I break down the symptoms of a common cold and provide a treatment option for each one. 

Everyone, at one time or another has had a cough ranging from a tickle in throat to a more productive cough with chest congestion. Please note that a cough accompanied by a high fever or shortness of breath requires intervention and evaluation by your health care team.

In addition if you have a cough that produces blood or thick colored mucus and lasts for longer than ten days, consult with your health care professional as well.

For minor irritation, which include scratchy throat, allergies, and uncomplicated cough of short duration (not accompanied by high fever or pussy mucus) here's what you can do to control it:

  1. Drink plenty of clear fluids. This simple solution can help diminish cough and will help keep secretions less viscous or thick. Meat or dairy products can make mucus secretions thicker. Than broth or chicken soup your mother may have recommended when you were young may be just what you need, avoiding large pieces of chicken and majoring on the healthy broth.
  2. Try a Lozenge. Lozenges or cough drops can help your cough by encouraging saliva production. Sugar free options are readily available, check labels for ingredients. Since there are so many lozenges without added sugar, it is best to use those where you can. If you are only using them occasionally, they probably won’t affect blood sugars a lot. Keep in mind, if you use a lot of lozenges in a day your sugar intake can add up, as many lozenges with added sugar contain as much as 3-4 g per piece. Information on sugar content is really available on labels.
  3. Be ware of dextromethorphan. This is the primary ingredients in cough medicine currently available over the counter. Although it should not impact blood sugars when taken at recommended doses, dextromethorphan can cause some dizziness and drowsiness especially when taken with other medications that may cause drowsiness such as anti-histamines  such as diphenhydramine.You will find this ingredient often labeled on products as DM. Check liquid formulations for sugar content; most that contain sugar have very little added sugars, some use artificial sweeteners. Check your labels and look for products with zero carbohydrate value if you can. Note that artificial sweeteners like aspartame and sucralose may be a part of liquid formulations. In general, it may be best to look for tablets so that you can avoid sweeteners altogether. For children, this may not be possible so check with you health care team, as small amounts of sugar in many products may not have a huge impact on blood sugars.


#1. Decongestants: Risky if You Have High Blood Pressure

Decongestants work by essentially causing a drying effect by constricting blood vessels. These products include, pseudoephedrine, phenylephrine, and oxymetazoline. Oxymetazoline is found in topical spray formulations such as some Afrin ® products and others.

Oral decongestants, by virtue of their mechanism of action can cause some unwanted side effects. They can raise blood pressure, so caution is advised when using these products if you have or are being treated for high blood pressure.

Decongestants can also increase pressure within the eye, so use with caution if you have eye conditions such as glaucoma. Since an increase in blood pressure may have an impact on the retina, these products may not be useful for people with existing retinopathy.

Again, refer to your own health care team for proper guidance. These decongestants can also cause fluctuations (generally increases) in blood sugars. When taking a decongestant, monitor blood sugars closely.  Blood sugars also can and usually do rise when you are ill, oftentimes compounding the issue. It is advised to avoid using topical or oral decongestants for more than 5-7 days in a row.

# 2. Anti-Mucolytics: Mostly Safe

Guaifenesin is an expectorant that helps loosen and get rid of excess phlegm or secretions or sputum. This is the active ingredient in many combination products and has been a mainstay in Robitussin ® products for many years.

This product has no adverse effects in patients with diabetes as a rule; other than some cough medicines having a higher sugar content than others. It is therefore important to check your labels. The product is also available in a pill form that has a bitter taste; avoid breaking or crushing tablets, as this won’t allow proper absorption of this time rebased product. Drink plenty of water when taking this expectorant, as this will aid in the effectiveness of the product.

#3. Anti-histamines: Low Blood Sugar Warning

Common medications include diphenhydramine, cetirizine, loratadine, fexofenadine; also known as Benadryl®, Zyrtec®, Claritin®, and Allergra®.

Anti-histamines are often used for allergies as they do blunt the histamine response which is a known cause of allergic reactions. They are also often recommended in conjunction with other medications to treat a cold as they do tend to have a drying effect and often help with sinus and runny nose symptoms.

Diphenhydramine is a common anti-histamine that is also a cough suppressant. It can, however, cause quite a bit of drowsiness and should generally not be taken when you need to be mentally alert such while driving or at work. Because of the side effect of drowsiness, this agent may interfere with symptoms of low blood sugar.

The newer anti-antihistamines  which include cetirizine, fexofenadine, and loratidinedo not have as profound effect on alertness, and thus are often preferred over older agents such as diphenhydramine, commonly known as Benadryl ®. Anti-histamines are available in liquid and tablet formulations.  

For General Aches and Pains

Your health care team may recommend analgesics such as ibuprofen or acetaminophen. Depending on your medical history, either one of these products will help reduce fever and overall aches and pain.

Ibuprofen is a bit stronger as a fever reducer and has some capacity to decrease inlammation. Acetaminophen, however, may interfere with some blood glucose meters and CGM’s; check with your manufacturer to see if this pertains to you.

It is important to stress again that if symptoms persist or are accompanied by high fever or difficulty breathing, to consult your health care team or proceed to an Urgent Care Center or local ER.

Illness, even if just a common cold can cause extreme fluctuations in blood sugars, and can therefore be dangerous in the patient with diabetes. 

Remember to tell your pharmacists if you choose to take any over the counter medications, as many of these can interact with prescriptions medications. Your pharmacist will advise you of the safest options for you. 

Caffeine Caution 

Keep in mind that caffeine is often contained in OTC medication combination and can potentially raise blood pressure; again read labels carefully. Taking OTC products for a few days may not impact blood sugars, but over time, oral decongestants such as pseudoephedrine for example can cause blood sugars to rise. Be cautious and use medications under supervision of your health care team.

Updated on: February 28, 2019
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