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What Are the Most Common Alpha Lipoic Acid Side Effects?

By Susan Elliott
Updated Mar 03, 2024
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Alpha lipoic acid, also known as ALA, doesn’t have many side effects, but the most common typically include low blood sugar and difficulty absorbing and retaining certain vitamins. A small percentage of the population might also experience an allergic reaction to ALA or other ingredients included in supplement materials. In general, the most serious side effects are usually experienced by people who suffer from certain existing conditions, namely diabetes and thyroid dysfunction. Most experts discourage pregnant and breastfeeding women from using it, too, since not a lot is known about how it can impact developing fetuses or infants.

ALA in General

ALA is an antioxidant, which means that it has the capability to prevent nearby molecules from oxidizing: a process that can sometimes lead to “free radicals,” or particles that aren’t anchored and can sometimes be prone to unchecked growth. Free radicals are thought to be responsible for certain cancers and other health issues. The human body naturally synthesizes some ALA, and the compound is readily available in nature, too particularly in root vegetables, leafy greens, and organ meats. It’s often referred to as the “universal antioxidant” because of its soluble properties; it dissolves in both water and fat.

Documented alpha lipoic side effects are linked exclusively to commercially produced supplements. There are not usually any reported side effects related to food sources. Most of this concerns concentration and dosage.

Some doctors recommend a daily dose of ALA for its antioxidant properties. The typical dosage of alpha lipoic acid is 800 mg per day. Anyone considering taking it should usually consult a physician, and if any alpha lipoic acid side effects occur, users should stop taking the supplement and seek medical attention. Even though most reactions are fairly mild, they can in some cases be a sign of a more serious condition.

Blood Sugar Issues

One of the most common alpha lipoic acid side effects is a quick drop in blood sugar, commonly within an hour or so of when the supplement was taken. Low blood sugar is known medically as “hypoglycemia,” and common symptoms include lightheadedness, dizziness, hunger, and irritability. The condition can usually be corrected by eating a snack or a small meal, but it can put stress on the heart and other organs if it happens frequently.

Special Considerations for Diabetics

People who suffer from diabetes are often at an increased risk of experiencing potentially harmful blood sugar drops and spikes. Diabetes is a disease that impacts how the pancreas processes sugar. Hypoglycemic reactions can be particularly dangerous for people who suffer from this condition, and as such diabetics should only use alpha lipoic acid supplements under medical supervision and with regular blood sugar checks.

Possible Vitamin Deficiencies

Supplementing with alpha lipoic acid might also contribute to thiamine deficiency, also known as a vitamin B1 deficiency. A sufficient level of thiamine is required in order for the body to properly use carbohydrates. People deficient in thiamine are at risk for cardiovascular, neurological, and gastrointestinal problems. The consumption of large amounts of alcohol while taking ALA supplements is believed to be the main cause for insufficient levels of thiamine in supplement users.


In rare cases, ALA supplements can cause allergic reaction, the side effects of which often include swelling, itching, and hives. Most of these reactions are mild, but they can be life-threatening if they impact a person’s airways. Anyone who suspects that he or she is suffering this sort of a reaction is usually wise to get immediate medical attention.

People With Thyroid Concerns

People who have thyroid disease, hypothyroidism, or hyperthyroidism might be more prone to experiencing things like heart palpitations and shortness of breath when taking the supplement. This is due to the fact that these supplements can interact with the use of thyroid medications like levothyroxine and Synthroid®. While heart palpitations are not usually fatal, they can be unpleasant. Studies show that small doses of alpha lipoic acid, such as those that occur naturally in some foods, are usually well tolerated by thyroid patients. High concentrations can be problematic, though.

During Pregnancy

Side effects may also be more pronounced in women who are pregnant or breastfeeding. Most care providers recommend that women in either circumstance avoid ALA entirely, since not a lot is known about how the compound could impact either the growing fetus or the breastfeeding child.

Who Should Not Take Alpha Lipoic Acid?

Alpha-lipoic acid serves one primary function: converting glucose into energy. This helps our bodies' cells use that energy when needed. Alpha-lipoic acid's solubility allows it to travel easily throughout the body. This ability allows every cell to get an adequate supply of ALA.

As mentioned earlier, alpha-lipoic acid is also an antioxidant that combats free radicals in our bodies. Why is this important? Free radicals are atoms that have unpaired electrons. They naturally try to bond with other atoms to solve this problem, causing DNA and cellular damage. Antioxidants supply the extra electrons that free radicals need, preventing them from bonding to other molecules.

These benefits are undisputed. However, ALA can pose problems for some individuals. You should check with your doctor if you take certain kinds of pharmaceuticals:

  • Oral diabetes medications
  • Insulin
  • Chemotherapy drugs
  • Thyroid hormones, such as Synthroid

Some diabetics take natural supplements to lower blood sugar. These often include cinnamon, chromium, fenugreek, garlic, and Panax ginseng. Don't take ALA if you're also using these supplements, as they can lower blood sugar to dangerous levels.

Other Precautions

You read earlier that diabetics should be cautious when taking ALA. Pregnant or nursing people should avoid ALA, as its potential effects on babies remain unknown. Meanwhile, ALA is also not recommended for those under 18 years old. More research is needed to understand how this antioxidant impacts children and teenagers.

Caution is needed for taking alpha-lipoic acid in a few other circumstances. People with liver disorders or thiamine deficiencies must consult their doctors before starting ALA supplements. Early studies suggest that ALA may help with liver regeneration, but more research is needed. People who consume large quantities of alcohol should also check with their doctors before taking ALA supplements.

Individuals scheduled for surgeries should discontinue using ALA about two weeks before their procedures. Blood sugar control can be compromised during recovery, and ALA can cause blood glucose levels to drop.

Alpha Lipoic Acid and Heart Palpitations

Why do some people experience heart palpitations while taking alpha-lipoic acid? Medication interactions are to blame in most cases. As mentioned previously, ALA can affect thyroid hormone medications such as Synthroid. Excess ALA levels can lower thyroid hormone levels, interfering with normal heart rhythms.

Alpha Lipoic Acid Side Effects: Hair Loss?

Does alpha-lipoic acid cause people to lose their hair? There's currently no evidence that ALA either triggers or reduces hair loss. However, other side effects are possible. You should keep these in mind if you're thinking about ALA supplements.

ALA is available in two forms: oral supplements and topical creams. The oral versions usually come in tablet or capsule form, with dosages between 100 and 600 milligrams. Meanwhile, ALA creams are applied directly to the skin. The U.S. Food and Drug Administration has not approved alpha-lipoic acid for medicinal use.

Side effects experienced with ALA can depend on the form you take. Some people ingesting oral ALA supplements have reported headaches, heartburn, vomiting and nausea. Those using ALA creams may occasionally develop rashes.

The Health Board is dedicated to providing accurate and trustworthy information. We carefully select reputable sources and employ a rigorous fact-checking process to maintain the highest standards. To learn more about our commitment to accuracy, read our editorial process.

Discussion Comments

By anon985034 — On Jan 13, 2015

I have nerve pain and am very interested in trying ALA, but I'm also hypothyroid. The article says not to take a large dose of ALA, but how much is large? 300 mg, 600, 900, what?

Is it useful to wait four hours after I take my levothyroxine? That's what is recommended before taking a calcium supplement.

By SteamLouis — On Aug 04, 2012

@burcinc-- I've actually been taking 800mg of ALA daily and I'm diabetic. I agree that diabetics need to be careful with this supplement and start off at the lowest possible dose and check their blood sugar. That's what I did and I have gone up to 800mg without side effects.

It can reduce blood sugar in some diabetics but not all. It hasn't done that with me. The only issue I have with it is upset stomach if I take ALA on an empty stomach. If I take it with my meal or afterward, I have no problems.

By burcinc — On Aug 03, 2012

This is a great article. It's very objective and straightforward!

There seems to be a common assumption that ALA is safe for diabetics. People, even diabetics themselves, think that since they suffer from high blood sugar, ALA will benefit them by lowering their sugar levels. That's not true because it could also lower it too much and cause a diabetic to go into a coma. And this applies not just to type one diabetics, but type two as well. Both are at risk for too high and too low blood sugar levels.

I'm not denying the benefits of alpha lipoic acid. But I also can't believe that some websites actually recommend ALA supplements to diabetics and that too, up to 800mg! That's pretty dangerous in my view! Diabetics should get their ALA naturally through foods like broccoli and spinach.

By ZipLine — On Aug 02, 2012

My friend is using this antioxidant and she keeps talking about alpha lipoic acid benefits. She says that it's really great. She has been feeling much more energetic and healthy since she started taking it.

I was excited to try it out too, but I guess I can't because I have hypothyroidism. I know a small dose might be okay, but I'd rather not take any risks. I take thyroid hormone medication every morning and some of the medication is in my system all the time. So it will probably counteract with ALA unfortunately.

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