Chronic coughs may be the result of an underlying fungal infection or perhaps a B12 deficiency. According to the study in the American Journal of Clinical Nutrition:
"This study suggests that [vitamin B-12 deficiency] may contribute to chronic cough by favoring sensory neuropathy as indicated by laryngeal hyper-responsiveness and increased NGF expression in pharyngeal biopsies of [vitamin B-12 deficiency] patients. [Vitamin B-12 deficiency] should be considered among factors that sustain chronic cough, particularly when cough triggers cannot be identified."

Using Essential Oils Orally for a Cough
We don’t promote casual internal use of essential oils and feel that they should only be used orally with respect for how concentrated the oils are. We want the consumer to have an understanding of how to administer, for what purpose, how much, which essential oils, safety concerns and so on, but Kurt Schnaubelt notes that a persistent cough is one condition that responds well to such use, when used appropriately.

In Robert Tisserand's Essential Oil Safety Masterclass (2022), Robert stated in a Q&A that he personally felt that ingesting eucalyptus capsules was very effective for respiratory issues.

Testimonies
1. I sprayed Plague Defense Spray around my house all evening to quiet a cough that all 3 of us had at the same time. Boy did it work, instantly, and my son fell right off to sleep (what a testimonial for the spray). – Diane

2. I had to write you and let you know that my cough is soooooo much better. I had been coughing for over a week and was not sleeping well. I combined a teaspoon of raw honey with 1 drop Plague Defense + 1 drop Lemon, mixed well with a toothpick, and then flipped the spoon over onto my tongue and let the honey mixture melt off the spoon onto my tongue and slowly down my throat. This avoided getting the essential oils on my lips. I slept so much better. I did wake up with one coughing fit, but it didn't last long and I was able to go right back to sleep. I have no idea what time it was even when I woke up, as I was so tired. I woke up this morning at 6:30 and did not feel the itching in my throat like I have. I took another dose this morning as I did have a little cough, but it is minor, and like I said, I don't have the itching. I also took some lemon by itself. I'm not feeling like I want to cough every 10 seconds either.  In fact, I am sitting here breathing normally instead of with little shallow breaths, and I do not have that constant urge to cough!  I did feel some sinus pressure, face swelling, and headache and took Lavender (a drop on the tongue, then held to the roof of the mouth) and rubbed some Headache Relief on, and that is now gone. I have to tell you that I have had these issues all my life, and while not life threatening, they were debilitating as I felt awful all the time. Nothing really seemed to work. I would end up having to go on steroid medications and did not like that at all -  Prednisone, steroid inhalers and steroid nasal sprays! There's just something not good about taking something that instructs you to rinse your mouth out really well after using it (because if you don't you can get a yeast infection in your mouth). That's just wrong! I started with the YL oils, and I have to say that I like Hopewell better.  Not only the cost and there's no MLM, but they actually seem to work better. I really appreciate what you have done. It is important to me to be able to believe in where I put my money. I believe in Hopewell Essential Oils.
UPDATE 3 days later: I am still so thrilled that the simple remedy worked. I am not coughing! Seriously, these oils work fast. I went from misery to having this cough under control. I did have a couple of coughing spells, but they were fewer than I had before the remedy. - C.W.

3. My little one with Down Syndrome seemed to turn every cold into chronic coughing or bronchitis, and the doctor told me he considered him asthmatic. This past winter was remarkably better. This is what we did:
- Added D3 as a supplement (used Source Naturals because of the tiny pill that was easy to swallow.
- Used Myrtle essential oil applications in his nostrils with a cotton swab [see Linda's tips on doing this in the Health Care file under Down Syndrome], Respiratory Relief on the soles of his feet nightly.
- Supplemented with a quality probiotic (Dr. Mercola has a good one).
- ½ a Mullein capsule sprinkled on his food at the first sign of a cold. I feel like this helped keep it from his lungs.
- Fed lots of bone broths and chicken broths
- Apple Cider Vinegar tonic (organic, unprocessed) helps to detach biofilm that is a colony of bacteria that becomes static rather than moving as individual bacteria does. They excrete a slime to protect themselves as a colony, so to speak. The slime makes it very resistant to many forms of treatment including antibiotics, and it make it difficult for the immune system to get rid of it. The tonic morning and evening works wonders.
- ACV tonic recipe:
1 TB Organic Apple Cider Vinegar
1 TB Raw honey (local honey is best)
1 cup pure water

4. For chest congestion, coughs and laryngitis, I keep a small jar of essential oil-laced honey in the cabinet. I stir about 6 drops Respiratory Relief and 4-6 drops Lemon essential oils in a 1oz jar of raw honey. By keeping it tightly closed in a dark cabinet it stays potent. When I feel the need for something to help clear my throat or my breathing passages, I dip the handle of a teaspoon into the honey 'cough syrup' and let it melt into my mouth. I hold it there long enough for the oils to be absorbed into my system before swallowing. It tastes a lot like the cough drops that have been in stores forever, but with this mixture, I know what I'm putting into my system and it works!

5. I read CW's testimony (#2 above), and it worked so well! I put a couple drops Plague Defense in a tablespoon of raw honey and let it run slowly down my throat. It killed my sore throat and stopped my horrible tickle coughs that nothing else seemed to work on.

6. I didn't have Plague Defense for CW's testimony (#2 above) so I just used Lemon for my 10-year-old who had a persistent cough that went on for days. After 5 minutes she was cured! Seriously, she probably only coughed a couple more times the rest of the day. She is cured!

7. I really like what I have seen so far with using your oils on my 3-year-old daughter. She recently had a cold, and a couple of nights she was coughing so much that she was throwing-up. I mixed a drop of Peppermint oil with raw honey and let it melt off the spoon on her tongue. Within 5 minutes she stopped coughing and slept through the night. This remedy worked much better than any cough syrup that the doctor ever gave us for her. The only reason I knew what to try was your testimony files. Thanks so much for all the time you have put into helping all of us!
[HEO's Comment: Peppermint is not recommend orally for children under 5 years.]

8. I suffered lung, allergies and sinus issues most of my life, and the absolute best remedy for me has been 2 drops Frankincense + 2 drops Respiratory Relief in a capsule. I fill the rest of the capsule with a carrier oil and take it as a suppository.

9. Several members of our family had terrible lung congestion, and we had miraculous results with Hyssop var decumbens and Frankincense (with a carrier oil) taken as a suppository.

10. Over the Christmas holidays I got a frustrating congestive cough and stuffy nose. I took Warrior twice a day for three days. I also rubbed Respiratory Relief on my chest, neck and back. My coughing stopped almost immediately, my nose dried up and cleared, which allowed me to sleep well, and I didn't miss a beat with all the family who'd gathered at our house for the week. I love your oils!

11. When my husband got coughs, he'd keep them for months on end. I read on your website some testimonies about using the oils as a rectal suppository, so I kept mentioning this to him, but he'd change the subject. Finally, he got frustrated with the cough enough to say he was willing to give it a try. I was excited because I figured it this worked on him, it would work for anybody! I put 4 drops of Lung Support in a capsule and filled the rest with Castor oil. He put it where it belonged and went back to work in his shop in our garage. When he came back in later, he exclaimed that he was cured. I don't think I ever heard him cough again. Woohooo, these oils are great!

12. I use your Plague Defense Spray for coughs and sore throats - it's fantastic.

13. For persistent coughs I blend:
10 parts Patchouli
3 parts Black Pepper
2 parts Peppermint
As needed (about 3 times daily), I fill put 3-4 drops in a capsule, then fill with a carrier oil and swallow a few times daily. Hyssop with a carrier oil as a rectal implant can wipe out a cough as well. Patchouli taken internally seems to do a good job of breaking up the mucus.

14. I had open heart by-pass surgery and then got pneumonia. This is an awful combination. I had to cough in order to clear my lungs, but coughing was terribly painful for my whole chest because of the surgery. I thought I'd rather die. Thankfully my good friend felt to offer my her Frankincense. I was so weak, and being in the hospital made some procedures suggested here not practical to say the least. Her idea was to add a few drops of Frankincense to my juice. This worked wonders for my congested lungs. I had not slept hardly at all since my surgery, and this made recovery even harder - I was so weak. I added 3 drops to my juice an hour before bedtime, and slept through the night (except for an occasional visit from a nurse to give me a breathing treatment, take my pulse or whatever). I have to believe that Frankincense saved my life. - Sharon

15. I used 1 drop of Myrtle in a teaspoon of honey to soothe my sore throat and persistent cough. It didn't taste great, but wasn't bad, and it work!

16. I got brave and tried a drop of Frankincense on my tongue, and my cough stopped in seconds and didn't return for a few hours. I did it again, and that was the end of it.

17. I added Black Spruce to my Plague Defense and diffused it for a bad cough that seemed like wanted to turn to pneumonia. The Spruce is said to carry the Plague Defense into the lower lobes of the lungs. Whatever it did, it worked very well. After two nights of breathing this, I had almost totally recovered.

18. I have been sick and ended up with a cough that would not go away. A friend of mine suggested that I try putting a drop of Lung Support under my tongue to see if it would help. I had already been using Respiratory Relief on my chest and diffusing Lung Support at night. I put one drop of Lung Support under my tongue, and instantly I could feel a difference in my throat! My throat/bronchial tube felt healed. No irritation at all. So now when I feel a little irritation in my throat, I just put a drop under my tongue and it goes away. Thank you so much for all your help with the oils. - Nina

19. My son was home sick for 3 days last week with an ear infection. That has cleared up, but they always seem to lead into congestion and cough for him. This is how tonight just went down: 3am: he woke up coughing uncontrollably, crying. 3:05: I applied Lung Support (to his chest, back and inner thighs) 3:15: All coughing subsided, he fell asleep. For all the sleepless, croupy nights we have had in the past 11 years. . . this is simply amazing. I will never again be without this oil blend. - Susan

20. For a cough, chop up an onion and put it on a plate next to the bed (or wherever baby is sleeping). I don't know how it works, but it always kicks a cough for my little ones. The room will smell like onion for a day or so, but it's worth it! - Julie

21. My 2.5-year-old son had a horrible, barky, croup sounding cough regularly until we started Lung Support and Respiratory Relief. I would alternate applying them on his chest, then his back. He has not had breathing treatments or steroid shots for at least 6 months now. The cough was sometimes painful. He would hold his throat and cry, which was also croupy sounding. I also diffused these oils through the night in his bedroom, adding Bergamot, which seemed to help. - Mary
[HEO's COMMENT: Due to Birch in Lung Support, it is not suitable for children.]

22.  I've got a sick kiddo. This morning, in addition to his fever, he also had a lot of primarily mucous in his throat. I thought to mix Lemon and Myrrh for some reason. Then I checked the website and saw that Elemi is also good for dealing with mucous. So I mixed all 3 with coconut oil and put it around his throat. He asked for it several times when it was time to "re-oil," so I asked him why he liked it so much. He said it restored his energy, it felt "cleansing" and removed "the dross" from his throat. - Lynn

23. This cough syrup formula works fabulously:
3 drops Rosalina (or Eucalyptus radiata)
1-2 drops Peppermint
3-4 drops Rosemary ct cineole
2 oz raw Honey
2 oz Marshmallow Tea cold infusion
I mix the oils and honey and keep stored in a glass jar. When we have coughs, I mix up what we'll use short-term: Equal amounts of the honey mixture and Marshmallow Tea (cold infusion). You could use filtered water if you don't have the Marshmallow Tea. I give a teaspoon by mouth as needed. Use with discretion for children.

24. I am not very experienced with essential oils, and I am a nurse by trade, so I am very skeptical when it comes to using essential oils to heal. However, I have a 12-year-old son that has suffered (and annoyed us ALL) with a chronic dry cough. We have been allergy tested, used any and all over-the-counter allergy medications, and NOTHING helped. He coughs ALL the time! I ordered Respiratory Relief to try as a last resort. We started by mixing it with coconut oil and rolling it on his chest, back and the bottoms of his feet in the morning and the night. I am not sure that there was much improvement, but may a little. So one last ditch effort, I bought a diffuser and put a few drops in and diffuse it near his bed every night. After about 3 nights, I have NOT heard a cough - not ONE! It has been about 2 weeks and still going strong!!! I love this stuff. I am now a believer! - Marcia

25. I used Goldenrod for walking pneumonia. I rubbed a couple drops between my hands, cupped my hands over my nose and inhaled very deeply 10 times, 3-4 times a day. I use Goldenrod for coughs all the time because it takes care of it almost instantly! - Julianna

26. Peroxidizer - Use 3% peroxide - 3 bottles of peroxide to 5 bottles of water in a cool mist humidifier. I use the ultrasonic humidifier because it cranks out more volume. Sit in front of it and breathe deeply - pathogens in the lungs and sinuses can't liver in an oxygen enriched environment. Usually the flu and so on is gone within 24 hours using this method. You can also put it by your bed or the bed of your children at night when flu and cold strikes. Some have also had good results adding a few drops of Lugols iodine solution, which sounds like a good idea to me. - Kay

27. I am up raring to go this morning after a night free from coughing spasms! I have done steam inhalations of Lung Support (and extra Ravintsara last night) for 2 nights now with fantastic success! The doctor had called in another Z-Pac and some prednisone which I was hesitant to take because the antibiotics had already not worked, but which I took anyway out of desperation. Of course, they were not working again. The steam inhalation at night for 10-15 minutes did the trick! I also rolled my inner thighs with diluted Lung Support which helped some, but direct steam worked best. Thank you as always! I knew if I found the right protocol with the oils they would work best! Blessings to you, your family, and the company in Jesus's name! - Jennifer

28. I have the flu or bad cold for the second time. Last night I read all the comments about treating a cough because I could not go to sleep. I began diffusing Plague Defense and put Vicks and Plague Defense on my inner thighs. I fell asleep quickly. It felt like magic! - Sandy

29. I applied Breathe Easy on my daughter's inner thighs and her coughing fit just stopped! It was crazy-awesome how fast that worked. Now my husband is doing it with Respiratory Relief! Thank you!!! - Leigh

30. My husband applied Warrior to his chest, back and feet. His cough was terrible! He has only used it 2 days and has shown drastic improvement! Within minutes he could breathe easier and his cough was more productive. The intensity of his cough became easier too. I'm so glad I had this on hand when we needed it. - Christine

31. My 82-year-old Grandma developed a chronic dry cough about a year ago. Hearing her up night after night, I started running my diffuser in her room alternating Breathe Easy, Lavender, Black Spruce and Lung Support. Within a week of diffusing the oils, her cough was gone! We have continued diffusing, as the cough comes back when we stop. There is something about the oils that her body must need. - Emily

32. After working on a chicken farm for about 5 months my mom started coughing constantly. I set up my trusty diffuser in her room. I alternated diffusing Lavender and Lung Support nightly. Three weeks later the cough resolved completely! I was so happy! - E. N.

33. I'm 18 weeks pregnant with congestion and a dry cough. I diffused Rosalina and it made my nose runny (because of it's mucolytic properties), but then all the problems vanished. No more congestion or coughing. I can breathe again! Love this oil! - Ellie

34. For a constant cough, I used one drop of four oils in honey [Lemon, Peppermint, Roman chamomile, Frankincense].  I did that the night before last and didn’t get the oils mixed in well, which did burn a bit, but the mixture worked for 3-4 hours. Then the next night I remembered reading something you had written on your website somewhere about how you’ve found things may work just as well topically, so I tried the same four oils in coconut oil and applied it on my feet and on my chest. This worked BETTER than by mouth. I so appreciate when you share what you do on your website. - Donna

35. Please extend a huge thank you and heaps of gratitude to your team! I never expected to order on Saturday morning and have my package out for delivery today, but it is greatly appreciated! My little guy started coughing EARLY Saturday morning so badly that he couldn't sleep and it sounded like it might be croup. It took me a couple hours, but I finally remembered that I had a sample bottle of Breathe Easy tucked away. Within minutes of applying it to his feet and inner thighs, I could see him visibly relax and he was finally able to sleep. - Heather

36. I applied Cleansing on the abdomen to help rid me of a cough I'd had for months. - Sunny

37. For coughs in our family, we diffuse Lung Support and apply it diluted to inner thighs. If there is worrisome congestion, we put a couple drops of Lung Support in a capsule and fill with coconut oil and use as a suppository. We also useVocal Rescue Spray frequently. - B.C.

References
Purchon, Nerys; Cantele, Lora, Complete Aromatherapy and Essential Oils Handbook for Everyday Wellness, pages 296-297.
Schnaubelt Ph.D., Kurt (2011-11-08). The Healing Intelligence of Essential Oils: The Science of Advanced Aromatherapy. Inner Traditions/Bear & Company. Kindle Edition.
Vintage Remedies Aromatic Medicine online class.
Webb, Mark, BS in Biochemistry and Plant Biology and Diplomas in Remedial Massage and Aromatherapy