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Ask A Doctor – CBD Safety, Side Effects & Correct Dosing

Written by Dr. Leah Zachar

When it comes to taking CBD, its well worth being aware of the safety aspects, side effect and correct dosing, so that you can get the most out of your medicine

Question: What are the common options for CBD delivery?

Sublingual – Oil tincture taken sublingually is considered one of the quickest ways to feel the effects. The onset is 5-20 minutes. It also offers a more exact measurability and tapering to achieve the optimum dose.

Oral (edibles, lozenges, beverages, tinctures, gel-caps) – The benefits of orally dosing is that the effects can last for hours, however the onset is slower that when CBD is vaped or taken sublingually. It is tasteless and offer a more discreet way of taking medication as it is in pill form.

Topical – (balms, cream, ointment) These are applied directly to the affected areas affected and are best when the source is at or directly below the skin surface. Examples include: rash, inflammation, sports injury.

Vape – Inhalation is good for treating acute symptoms that require immediate attention; the effects can be felt within a minute or two, but the affects usually dissipate within a couple of hours.

Question: How do I figure out the dosage that is best for me?

Everyone is different. Here are a few tips:

When beginning CBD, start with the smallest dose possible because everyone reacts differently. You need to “know your body”, so you can gage how your body responds to the CBD.

Viva 300-mg/one-ounce bottle, as an example, makes it very easy to start small and slowly work up to your desired dose.

Pay attention to the dose you are taking as you taper up. The right dose varies from person to person. CBD is lipid soluble, so heavier & younger people may require a larger dose than lighter & older people.

Involve your PCP. If you are taking CBD for a medical condition, you should let your doctor know. Other medications you are taking – especially if they require very specific serum blood levels, may need to be adjusted. This is not usually the case, but it is always wise to be careful.

Stay involved with CBD testers. We are here to help you. Send us any questions you have. We will answer them and if we can’t, we will help you find someone who can.

There is a ‘sweet spot’ with CBD based on each person’s individual endocannabinoid system. So, what works for you isn’t necessarily what’s going to work for someone else.

Question: What are the Side effects of CBD

CBD is metabolized in the liver. It inhibits the metabolism of some medications broken down by Cytochrome P450 3A4 & Cytochrome P450 2C19. The most important medications to be concerned about are the antiepileptic medications and medications requiring monitoring of serum levels (like warfarin). Therefore, if you are on any of these medications, your PCP, neurologist, or cardiologist should be involved in your care.

If you are taking sublingual CBD, there is a rare side effect of “cotton mouth”, which produces the symptom of thirst. The dry mouth sensation is caused by the decreased salivary production that occurs when sublingual CBD is used.

Increased tremor in tremor in Parkinson’s disease at high dose CBD. This is controversial however. Many studies show that there is no increase in tremor. Nonetheless, if it presents, lowering the dose of the CBD will resolve the symptom.

Is CBD safe?

CBD is safe. There are no untoward effects when taken in excess. Doses of 4,000-mg a day have been taken safely.

Is there a dose that is toxic?

No. There is no dose that is toxic. In this regard, CBD functions very much like a vitamin. When you take too many “One-a-day” vitamins, your body uses what it needs, and you urinate out the rest. When you take an excess of CBD, the CBD stabilizes your body’s endocannabinoid system, and then the “excess” CBD is eliminated by the body’s excretory system.

What is the best delivery system for CBD?

It depends what you are trying to treat, how quickly you want the CBD to take effect, & how long you want the effects to last.

In most cases, tinctures are best to start with. This is because you don’t know initially what dose is going to be best for you. Everyone has a dose that “fits” them. Once you find the right dose, then you should pick the delivery system that best suits your lifestyle.

For instance, if you have anxiety, you may want to use tinctures to tailor up to the dose best suited for you, and then when you are stabilized, continue with the sublingual CBD oil or if you prefer, switch to soft-gels.

If you have ulcerative colitis, you would be best using soft-gels because you want the CBD to work directly at the site of the problem – the intestinal lining.

If you have a rash, a CBD balm would be preferred, because this can be applied directly to the rash.

If you have back pain which is neuropathic (present for three months or longer), you might want to start with CBD tincture, so you can taper up to find the best dose, and then have the option of switching to soft-gels.

If you have a seizure disorder or schizophrenia, where high doses are usually needed, you may want to use high potency soft-gels, as this is the most efficient way to ingest high doses.

If you have insomnia, you may want to start with CBD tincture sublingual and then switch to soft-gels depending on the dose best suited to promote a restful sleep.

But in all cases, start low, and go slow. Not everyone responds to the same dose.

To treat a specific problem, it is necessary to take the correct dose.

Here is a general guide:

  • Chronic pain: 2.5-20-mg CBD x one month
  • Epilepsy: 200-300-mg CBD x four months
  • Sleep disorders: 40-160-mg of CBD
  • Schizophrenia: 40-1,280-mg CBD

Multiple sclerosis symptom: Cannabis plant extracts containing 2.5-120 mg of THC-CBD combo po QD x 2-15 wks.    A mouth spray might contain 2.7 mg of THC and 2.5 milligrams of CBD at doses of 2.5-120 mg for up to 8 wks.   Use 8 sprays within any 3 hrs, with a max of 48 sprays in 24 hr.

There are so many more ailments that CBD can address, but the dose varies with each patient. A clue in dosing should be that the higher the dose, the more sedating the CBD effects can be. That is why doses to help insomnia, epilepsy, and schizophrenia are higher than the dose required for pain.

Question: CBD has biphasic properties. What does biphasic mean?

Biphasic means that CBD has different effects on the body at different doses. CBD words by interacting with the endocannabinoid system. At lower doses, CBD can increase wakefulness, alertness, and elevate the mood. At higher doses, CBD has an anxiolytic & sedating effect.

If the dose taken is too low, or too high, CBD may not produce the desired effect.

An example of a biphasic drug is alcohol. At low amounts, alcohol acts as a stimulant. However, as the amount of alcohol ingested increases further, it begins to act as a depressant, ultimately causing one to “pass out”.

In CBD dosing, for example, patients who take 15-mg may have periods of wakefulness during sleep, but when they increase the dose (slowly) to 160-mg, they notice an increase in sleep duration.

“Less is more” is often the case with respect to cannabis therapy.

Caution regarding the biphasic effect of THC: Too much THC, while not lethal, can amplify anxiety and mood disorders.

Can CBD give you low blood pressure?

That is a myth. CBD blunts the cardiac response to stress by its anxiolytic & analgesic effects. As the number one cause of death is cardiac, it has been proposed by some that CBD may be shown soon to be beneficial to all people with known cardiac disease due to these benefits.

How long do you hold a tincture under your tongue?

Leave it under your tongue and give it some time to absorb over a minute or two. After that, you can swallow it.

When would soft-gels be preferred to sublingual CBD?

Active smokers should not take sublingual’s CBD because smoking decreases the absorption of sublingual medication. Smoking causes vasoconstriction of the blood vessels in the oral cavity. However, is a smoker DOES take sublingual CBD, the CBD will still get into the body, because instead of being absorbed under the tongue, the tincture will eventually be swallowed and absorbed in the digestive tract – that same way soft-gels work. 

Does CBD convert into THC when it is digested?

No. This occurred in trace amounts in the laboratory studies, but when it was studied in human beings, this was found NOT to be true.

Where is CBD metabolized?

In the liver. In the liver it is metabolized by P450 enzymes. This enzyme group metabolizes many of the conventional medications prescribed. CBD may displace other medications and prevent them from being broken down. Thus, there may be a higher level in the bloodstream of other medications. While this is usually not clinically important, it is wise to discuss this with your PCP – especially when taking antiepileptic medication or medication that require periodic monitoring to maintain a certain serum blood level.

Interesting tidbit about CBD and the liver:

CBD is metabolized in the liver. The main metabolite of CBD is hydroxylated 7-COOH. Research is currently underway in a British biopharmaceutical company because it seems that the metabolite of CBD can treat non-alcoholic fatty liver disease. Many Americans may already be aware that NAFLD is the #1 cause of liver disease in the United States.

Question: Which agent and delivery and dose are the best for back pain?

It depends on what caused the back pain, and how long you’ve had the back pain. If the back pain is recent and muscular, using tincture sublingually would suffice. Start at 2-3 mg (which is 2-3 drops) and taper up slowly. Go as high as you feel necessary. Not only will the CBD help the spasm, but it will relax the muscles and allow you to recover quicker.

Question: I have gut inflammation, food allergies and sensitives, skin infection, fatigue, candida. So, the question is if the cannabis oil will help and how?

I would start with low dose oral medication because the most effective way to reduce inflammation of the intestinal lining is to take a medication that works at that site. Start with a low dose & increase it slowly.

As per your request, we are moving the weekly In-house doctor session from Thursday at 1 pm EST, to Thursday at 3 pm EST (That’s UK’s 20:00, NYC’s 15:00 and LA’s 12:00)

If you want to read more from Dr Zachar, check out: ‘Ask A Doctor – CBD Interactions And Neuropathic Pain

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About the author

Dr. Leah Zachar

Dr. Leah Zachar, M.D. is a physician who worked for nearly thirty years in Internal Medicine.
She currently is a scientific adviser to CBD Testers. Dr. Zachar believes that there is much that medical cannabis, and cannabidiol in particular can offer to traditional medicine.