Who Should Not Take GABA

GABA is sold over the counter and is considered a well-tolerated supplement, so contraindications to it are rarely mentioned. However, there are groups of people for whom taking it may be risky or simply unstudied. The editorial team has gathered absolute and relative cautions and explained what they are based on.

Why supplements can have contraindications too

Unlike medicines, dietary supplements do not undergo registration clinical trials with mandatory study of contraindications. Therefore the instructions on GABA packages are often limited to the standard phrase about individual intolerance, pregnancy, and breastfeeding.

This does not mean there are no other restrictions. Contraindications for a supplement can be derived from three sources: the known pharmacological effects of the substance, described interactions, and gaps in research. For GABA the first source is the effect on blood pressure and a possible sedative effect, the second is combination with drugs acting on the nervous system, the third is the absence of data for certain groups.

The safety review by the United States Pharmacopeia (Oketch-Rabah et al., 2021) concluded that at doses typical for supplements, GABA is not associated with serious health risks for healthy adults. The key words here are "healthy adults": they were precisely the main participants in the studies.

So all the cautions below concern people who fall outside this group: pregnant women, children, people with chronic conditions, or those taking medications. For them, the decision to take GABA should be made by a doctor, not a salesperson in a sports-nutrition store.

Pregnancy, breastfeeding, children, and adolescents

For pregnant and breastfeeding women, there are no safety studies of GABA supplements. The USP review specifically notes the lack of such data. In this situation the general principle of pharmacology applies: in the absence of evidence of safety, a substance that affects the nervous and endocrine systems is not used without clear medical indications.

It is worth remembering that in experiments GABA affected the secretion of growth hormone and prolactin (Cavagnini et al., 1980). Although the practical significance of these changes for pregnancy is unknown, it is precisely such hormonal effects that are an additional reason for caution.

Children and adolescents were also not participants in most studies. At this age the nervous system continues to mature, and the GABAergic system plays an important role in this. Sleep or concentration problems in a child require examination by a pediatrician or pediatric neurologist, not a supplement from a store.

Young athletes who train intensely and imitate adults in choosing supplements should be told: sleep and recovery at this age are ensured by routine, nutrition, and sensible loads. None of the "relaxing" supplements has been studied for adolescents.

Cardiovascular conditions and blood-pressure medications

GABA is able to lower blood pressure — this effect was shown, in particular, in the study by Inoue et al. (2003) with fermented milk enriched with GABA in people with mild hypertension. For a healthy person the decrease is small, but in certain situations it becomes clinically significant.

For people taking antihypertensive drugs — ACE inhibitors, angiotensin receptor blockers, beta-blockers, diuretics, calcium channel blockers — GABA may add a hypotensive effect. Dizziness, weakness, and fainting are possible with a sharp change in body position.

For people with chronic hypotension and a predisposition to orthostatic reactions, the editorial team also advises refraining from taking it on their own. For athletes the risk increases after long workouts with fluid loss, in the heat, after a sauna.

Signs of excessive lowering of pressure at which intake should be stopped and a doctor consulted:

• dizziness or darkening in the eyes when standing up;
• pronounced weakness, sweating, nausea;
• episodes of a near-fainting state or fainting;
• rapid heartbeat at rest.

If a doctor has nonetheless permitted GABA, it is reasonable in the first days to monitor pressure at home, take the supplement in the evening in a position where you do not need to stand up abruptly, and inform the doctor of any episodes of dizziness.

Neurological conditions and psychoactive drugs

People taking benzodiazepines, Z-hypnotics (zolpidem, zopiclone), barbiturates, gabapentinoids, baclofen, or first-generation antihistamines should not add GABA on their own. These drugs have a pronounced sedative action, and combining them with other agents affecting inhibition may enhance it.

A special group is people with epilepsy. Antiepileptic therapy is often aimed precisely at the GABAergic system, and the doctor carefully selects the dose. Although the GABA supplement probably penetrates the brain poorly, any changes in the "GABAergic" background without the neurologist's knowledge are undesirable.

People being treated for anxiety, depressive, or bipolar disorders should also discuss any supplements with a doctor. Independent intake of "calming" agents can mask symptoms, complicate the assessment of therapy effectiveness, and change its tolerability.

Separately — people with a history of dependence on alcohol or sedative substances. GABA itself is not considered a substance that causes dependence, but products with hidden phenibut, which has a pronounced dependence potential, appear on the market. For this group, choosing only verified mono-products is especially important.

Other situations requiring caution

Liver and kidney disease.There are no clinical data on taking GABA in severe chronic liver and kidney disease. Since these organs are responsible for the metabolism and elimination of many substances, people with such diagnoses should coordinate any supplements with a doctor.

Preparation for surgery.The general practice is to inform the anesthesiologist about all supplements a person takes. For agents with potential sedative action this is especially relevant: the anesthesiologist will decide whether intake needs to be stopped in advance.

Driving and dangerous work.Even in healthy people GABA can cause drowsiness. Do not take it before driving, working at height, or with machinery until you know your own reaction.

Athletes under doping control.GABA is not banned by WADA, but contaminated products pose a risk. Athletes who undergo testing should choose products with independent certification.

Individual intolerance.Allergic reactions to GABA itself are not described as a common phenomenon, but a reaction to excipients, dyes, or other components of complexes is possible. If a rash, itching, or swelling appears, intake should be stopped immediately.

Editorial conclusions

For healthy adults, GABA at label doses is considered relatively safe, but this assessment does not extend to everyone.

Without a doctor's consultation, GABA should not be taken by pregnant and breastfeeding women, children, people with epilepsy, or those taking sedative, hypnotic, antiepileptic drugs or blood-pressure medications.

The absence of described problems in a certain group often means not safety but the absence of research. In such cases, caution is a reasonable strategy.

Read more about the risks in our materials "Side Effects of GABA," "What to Combine GABA With," and "Myths About GABA."

References

1. Oketch-Rabah HA, Madden EF, Roe AL, Betz JM. United States Pharmacopeia (USP) safety review of gamma-aminobutyric acid (GABA). Nutrients. 2021;13(8):2742.
2. Inoue K, Shirai T, Ochiai H, et al. Blood-pressure-lowering effect of a novel fermented milk containing gamma-aminobutyric acid (GABA) in mild hypertensives. Eur J Clin Nutr. 2003;57(3):490–495.
3. Cavagnini F, Invitti C, Pinto M, et al. Effect of acute and repeated administration of gamma aminobutyric acid (GABA) on growth hormone and prolactin secretion in man. Acta Endocrinol (Copenh). 1980;93(2):149–154.
4. Hepsomali P, Groeger JA, Nishihira J, Scholey A. Effects of oral gamma-aminobutyric acid (GABA) administration on stress and sleep in humans: a systematic review. Front Neurosci. 2020;14:923.
5. Boonstra E, de Kleijn R, Colzato LS, et al. Neurotransmitters as food supplements: the effects of GABA on brain and behavior. Front Psychol. 2015;6:1520.
6. World Anti-Doping Agency. The World Anti-Doping Code International Standard: Prohibited List. Montreal: WADA; оновлюється щорічно.