A more extreme treatment includes kidney or liver transplant from a donor without the condition. The foreign organs will produce a functional version of the defective enzymes and digest the methylmalonic acid, however all of the disadvantages of organ transplantation are of course applicable in this situation. There is evidence to suggest that the central nervous system may metabolize methylmalonic-CoA in a system isolated from the rest of the body. If this is the case, transplantation may not reverse the neurological effects of methylmalonic acid previous to the transplant or prevent further damage to the brain by continued build up.

Treatment consists of dietary protein restriction, particularly leucine. During acute episodes, glycine is sometimes given, which conjugates with isovalerate forming isovalerylglycine, or carnitine which has a similar effect.

Elevated 3-hydroxyisovaleric acid is a clinical biomarker of biotin deficiency. Without biotin, leucine and isoleucine cannot be metabolized normally and results in elevated synthesis of isovaleric acid and consequently 3-hydroxyisovaleric acid, isovalerylglycine, and other isovaleric acid metabolites as well. Elevated serum 3-hydroxyisovaleric acid concentrations can be caused by supplementation with 3-hydroxyisovaleric acid, genetic conditions, or dietary deficiency of biotin. Some patients with isovaleric acidemia may benefit from supplemental biotin. Biotin deficiency on its own can have severe physiological and cognitive consequences that closely resemble symptoms of organic acidemias.

Carnitor - an L-carnitine supplement that has shown to improve the body's metabolism in individuals with low L-carnitine levels. It is only useful for Specific fatty-acid metabolism disease.

The primary treatment method for fatty-acid metabolism disorders is dietary modification. It is essential that the blood-glucose levels remain at adequate levels to prevent the body from moving fat to the liver for energy. This involves snacking on low-fat, high-carbohydrate nutrients every 2–6 hours. However, some adults and children can sleep for 8–10 hours through the night without snacking.

Treatment for all forms of this condition primarily relies on a low-protein diet, and depending on what variant of the disorder the individual suffers from, various dietary supplements. All variants respond to the levo isomer of carnitine as the improper breakdown of the affected substances results in sufferers developing a carnitine deficiency. The carnitine also assists in the removal of acyl-CoA, buildup of which is common in low-protein diets by converting it into acyl-carnitine which can be excreted in urine. Though not all forms of methylmalonyl acidemia are responsive to cobalamin, cyanocobalamin supplements are often used in first line treatment for this disorder. If the individual proves responsive to both cobalamin and carnitine supplements, then it may be possible for them to ingest substances that include small amounts of the problematic amino acids isoleucine, threonine, methionine, and valine without causing an attack.

Currently, no cure for Zellweger syndrome is known, nor is a course of treatment made standard. Infections should be guarded against to prevent such complications as pneumonia and respiratory distress. Other treatment is symptomatic and supportive. Patients usually do not survive beyond one year of age.

The malabsorption resulting from lack of bile acid has resulted in elemental formula being suggested, which are low in fat with < 3% of calories derived from long chain triglycerides (LCT). However, reduced very long chain fatty acids (VLCFA) has not been shown to reduce blood VLCFA levels , likely because humans can endogenously produce most VLCFA. Plasma VLCFA levels are decreased when dietary VLCFA is reduced in conjunction with supplementation of Lorenzo’s oil (a 4:1 mixture of glyceryl trioleate and glyceryl trierucate) in X-ALD patients . Since docosahexaenoic acid (DHA) synthesis is impaired [59], DHA supplementation was recommended, but a placebo-controlled study has since showed no clinical efficacy . Due to the defective bile acid synthesis, fat soluble supplements of vitamins, A, D, E, and K are recommended.

Usually MSUD patients are monitored by a dietitian. Liver transplantation is another treatment option that can completely and permanently normalise metabolic function, enabling discontinuation of nutritional supplements and strict monitoring of biochemistry and caloric intake, relaxation of MSUD-related lifestyle precautions, and an unrestricted diet. This procedure is most successful when performed at a young age, and weaning from immunosuppressants may even be possible in the long run. However, the surgery is a major undertaking requiring extensive hospitalisation and rigorous adherence to a tapering regime of medications. Following transplant, the risk of periodic rejection will always exist, as will the need for some degree of lifelong monitoring in this respect. Despite normalising clinical presentation, liver transplantation is not considered a cure for MSUD. The patient will still carry two copies of the mutated BKAD gene in each of their own cells, which will consequently still be unable to produce the missing enzyme. They will also still pass one mutated copy of the gene on to each of their biological children. As a major surgery the transplant procedure itself also carries standard risks, although the odds of its success are greatly elevated when the only indication for it is an inborn error of metabolism. In absence of a liver transplant, the MSUD diet must be adhered to strictly and permanently. However, in both treatment scenarios, with proper management, those afflicted are able to live healthy, normal lives without suffering the severe neurological damage associated with the disease.

A diet with carefully controlled levels of the amino acids leucine, isoleucine, and valine must be maintained at all times in order to prevent neurological damage. Since these three amino acids occur in all natural protein, and most natural foods contain some protein, any food intake must be closely monitored, and day-to-day protein intake calculated on a cumulative basis, to ensure individual tolerance levels are not exceeded at any time. As the MSUD diet is so protein-restricted, and adequate protein is a requirement for all humans, tailored metabolic formula containing all the other essential amino acids, as well as any vitamins, minerals, omega-3 fatty acids and trace elements (which may be lacking due to the limited range of permissible foods), are an essential aspect of MSUD management. These complement the MSUD patient's natural food intake to meet normal nutritional requirements without causing harm. If adequate calories cannot be obtained from natural food without exceeding protein tolerance, specialised low protein products such as starch-based baking mixtures, imitation rice and pasta may be prescribed, often alongside a protein-free carbohydrate powder added to food and/or drink, and increased at times of metabolic stress. Some patients with MSUD may also improve with administration of high doses of thiamine, a cofactor of the enzyme that causes the condition.

Supplementary "protein substitute" formulas are typically prescribed for people PKU (starting in infancy) to provide the amino acids and other necessary nutrients that would otherwise be lacking in a low-phenylalanine diet. Tyrosine, which is normally derived from phenylalanine and which is necessary for normal brain function, is usually supplemented. Consumption of the protein substitute formulas can actually reduce phenylalanine levels, probably because it stops the process of protein catabolism from releasing Phe stored in the muscles and other tissues into the blood. Many PKU patients have their highest Phe levels after a period of fasting (such as overnight), because fasting triggers catabolism. A diet that is low in phenylalanine but does not include protein substitutes may also fail to lower blood Phe levels, since a nutritionally insufficient diet may also trigger catabolism. For all these reasons, the prescription formula is an important part of the treatment for patients with classic PKU.

The oral administration of tetrahydrobiopterin (or BH4) (a cofactor for the oxidation of phenylalanine) can reduce blood levels of this amino acid in some people. Most people, however, have little or no benefit.

Tentative evidence supports dietary supplementation with large neutral amino acids (LNAAs). The LNAAs (e.g. leu, tyr, trp, met, his, ile, val, thr) may compete with phe for specific carrier proteins that transport LNAAs across the intestinal mucosa into the blood and across the blood–brain barrier into the brain. It use is really only indicated in adults who will not follow an appropriate diet.

Another interesting treatment strategy for is casein glycomacropeptide (CGMP), which is a milk peptide naturally free of Phe in its pure form CGMP can substitute the main part of the free amino acids in the PKU diet and provides several beneficial nutritional effects compared to free amino acids. The fact that CGMP is a peptide ensures that the absorption rate of its amino acids is prolonged compared to free amino acids and thereby results in improved protein retention and increased satiety compared to free amino acids. Another important benefit of CGMP is that the taste is significantly improved when CGMP substitutes part of the free amino acids and this may help ensure improved compliance to the PKU diet.

Furthermore, CGMP contains a high amount of the phe lowering LNAAs, which constitutes about 41 g per 100 g protein and will therefore help maintain plasma phe levels in the target range.

The effects of drug-related dysgeusia can often be reversed by stopping the patient's regimen of the taste altering medication. In one case, a forty-eight-year-old woman who was suffering from hypertension was being treated with valsartan. Due to this drug's inability to treat her condition, she began taking a regimen of eprosartan, an angiotensin II receptor antagonist. Within three weeks, she began experiencing a metallic taste and a burning sensation in her mouth that ceased when she stopped taking the medication. When she began taking eprosartan on a second occasion, her dysgeusia returned. In a second case, a fifty-nine-year-old man was prescribed amlodipine in order to treat his hypertension. After eight years of taking the drug, he developed a loss of taste sensation and numbness in his tongue. When he ran out of his medication, he decided not to obtain a refill and stopped taking amlodipine. Following this self-removal, he reported experiencing a return of his taste sensation. Once he refilled his prescription and began taking amlodipine a second time, his taste disturbance reoccurred. These two cases suggest that there is an association between these drugs and taste disorders. This link is supported by the "de-challenge" and "re-challenge" that took place in both instances. It appears that drug-induced dysgeusia can be alleviated by reducing the drug's dose or by substituting a second drug from the same class.

In addition to the aforementioned treatments, there are also many management approaches that can alleviate the symptoms of dysgeusia. These include using non-metallic silverware, avoiding metallic or bitter tasting foods, increasing the consumption of foods high in protein, flavoring foods with spices and seasonings, serving foods cold in order to reduce any unpleasant taste or odor, frequently brushing one's teeth and utilizing mouthwash, or using sialogogues such as chewing sugar-free gum or sour-tasting drops that stimulate the productivity of saliva. When taste is impeded, the food experience can be improved through means other than taste, such as texture, aroma, temperature, and color.

Treatment centers on limiting intake of ammonia and increasing its excretion. Dietary protein, a metabolic source of ammonium, is restricted and caloric intake is provided by glucose and fat. Intravenous arginine (argininosuccinase deficiency) sodium phenylbutyrate and sodium benzoate (ornithine transcarbamoylase deficiency) are pharmacologic agents commonly used as adjunctive therapy to treat hyperammonemia in patients with urea cycle enzyme deficiencies. Sodium phenylbutyrate and sodium benzoate can serve as alternatives to urea for the excretion of waste nitrogen. Phenylbutyrate, which is the product of phenylacetate, conjugates with glutamine to form phenylacetylglutamine, which is excreted by the kidneys. Similarly, sodium benzoate reduces ammonia content in the blood by conjugating with glycine to form hippuric acid, which is rapidly excreted by the kidneys. A preparation containing sodium phenylacetate and sodium benzoate is available under the trade name Ammonul.

Acidification of the intestinal lumen using lactulose can decrease ammonia levels by protonating ammonia and trapping it in the stool. This is a treatment for hepatic encephalopathy.

Treatment of severe hyperammonemia (serum ammonia levels greater than 1000 μmol/L) should begin with hemodialysis if it is otherwise medically appropriate and tolerated.

There is no known cure for CVS, but there are medications that can be used for treatment, intervention, and prevention. There is a growing body of publications on both individual cases and the experiences of the CVS cohort. Treatment is usually on an individual basis, based on trial and error.

The most common therapeutic strategies for those already in an attack are maintenance of salt balance by appropriate intravenous fluids and, in some cases, sedation. Having vomited for a long period prior to attending a hospital, patients are typically severely dehydrated. For a number of patients, potent anti-emetic drugs such as ondansetron (Zofran) or granisetron (Kytril), and dronabinol (Marinol) may be helpful in either preventing an attack, aborting an attack, or reducing the severity of an attack. Lifestyle changes may be recommended, such as extended rest and reduction of stress. Because the symptoms of CVS are similar (or perhaps identical) to those of the disease well-identified as "abdominal migraine", treatment of CVS with a regimen of anti-migraine drugs, such as topiramate and amitriptyline, is showing promise in preventing recurrent attacks.

PKU is not curable. However, if PKU is diagnosed early enough, an affected newborn can grow up with normal brain development by managing and controlling phenylalanine ("Phe") levels through diet, or a combination of diet and medication.

Treatment or management of organic acidemias vary; eg see methylmalonic acidemia, propionic acidemia, isovaleric acidemia, and maple syrup urine disease.

As of 1984 there were no effective treatments for all of the conditions, though treatment for some included a limited protein/high carbohydrate diet, intravenous fluids, amino acid substitution, vitamin supplementation, carnitine, induced anabolism, and in some cases, tube-feeding.

As of 1993 ketothiolase deficiency and other OAs were managed by trying to restore biochemical and physiologic homeostasis; common therapies included restricting diet to avoid the precursor amino acids and use of compounds to either dispose of toxic metabolites or increase enzyme activity.

The primary treatment for type 1 tyrosinemia is nitisinone (Orfadin) and restriction of tyrosine in the diet. Nitisinone inhibits the conversion of 4-OH phenylpyruvate to homogentisic acid by 4-Hydroxyphenylpyruvate dioxygenase, the second step in tyrosine degradation. By inhibiting this enzyme, the accumulation of the fumarylacetoacetate is prevented. Previously, liver transplantation was the primary treatment option and is still used in patients in whom nitisinone fails.

Since the conversion of dihydroxyphenylserine (Droxidopa; trade name: Northera; also known as L-DOPS, L-threo-dihydroxyphenylserine, L-threo-DOPS and SM-5688), to norepinephrine bypasses the dopamine beta-hydroxylation step of catecholamine synthesis, L-Threo-DOPS is the ideal therapeutic agent. In humans with DβH deficiency, L-Threo-DOPS, a synthetic precursor of noradrenaline, administration has proven effective in dramatic increase of blood pressure and subsequent relief of postural symptoms.

L-DOPS continues to be studied pharmacologically and pharmacokinetically and shows an ability to increase the levels of central nervous system norepinephrine by a significant amount. This is despite the fact that L-DOPS has a relative difficulty crossing the blood-brain barrier when compared to other medications such as L-DOPA. When used concurrently, there is evidence to show that there is increased efficacy as they are both intimately involved and connected to the pathway in becoming norepinephrine.

There is hope and evidence that L-DOPS can be used much more widely to help other conditions or symptoms such as pain, chronic stroke symptoms, and progressive supranuclear palsy, amongst others. Clinically, L-DOPS has been already shown to be helpful in treating a variety of other conditions related to hypotension including the following:

- Diabetes induced orthostatic hypotension

- Dialysis-induced hypotension

- Orthostatic intolerance

- Familial amyloidotic polyneuropathy

- Spinal Cord Injury related hypotension

Empirical evidence of mild effectiveness has been reported using mineralocorticoids or adrenergic receptor agonists as therapies.

Other medications that can bring relief to symptoms include:

- phenylpropanolamine- due to pressor response to vascular α-adrenoceptors

- indomethacin

Vitamin C (ascorbic acid) is also a required cofactor for the Dopamine beta hydroxylase enzyme. Recent research has shown that vitamin C rapidly catalyzes the conversion of dopamine to norepinephrine through stimulation of the dopamine beta hydroxylase enzyme.

Untreated individuals with DβH deficiency should avoid hot environments, strenuous exercise, standing still, and dehydration.

There is no agreed treatment protocol. In most reported cases of ORS the attempted treatment was antidepressants, followed by antipsychotics and various psychotherapies. Little data are available regarding the efficacy of these treatments in ORS, but some suggest that psychotherapy yields the highest rate of response to treatment, and that antidepressants are more efficacious than antipsychotics (response rates 78%, 55% and 33% respectively). According to one review, 43% of cases which showed overall improvement required more than one treatment approach, and in only 31% did the first administered treatment lead to some improvement.

Pharmacotherapies that have been used for ORS include antidepressants, (e.g. selective serotonin reuptake inhibitors, tricyclic antidepressants, monoamine oxidase inhibitors), antipsychotics, (e.g. blonanserin, lithium, chlorpromazine), and benzodiazepines. The most common treatment used for ORS is SSRIs. Specific antidepressants that have been used include clomipramine.

Psychotherapies that have been used for ORS include cognitive behavioral therapy, eye movement desensitization and reprocessing.

Another treatment option is the topical solution of cocaine HCl which also provides relief for a short time period by acting as an anesthetic and desensitizing the nasal neurons. The topical solution is applied on the nostril. This topical solution can have several side effects as it has been found that some patients suffering from troposmia started to show symptoms of phantosmia after its use. Other patients have lost complete function of the nostril where the drug was applied.

Many patients seeking a quick form of relief achieved it by rinsing the nose with a saline solution. This treatment option is easily available and can be repeated several times throughout the day to obtain relief. An example of a nasal spray that can be used to alleviate symptoms is Oxymetazoline HCl, which seems to provide relief for a longer time period. The relief achieved by the use of nasal sprays seems to be because it results in the blockage of the nostril that does not allow any air to enter the olfactory cleft.

On 9 May 2014, the UK National Screening Committee (UK NSC) announced its recommendation to screen every newborn baby in the UK for four further genetic disorders as part of its NHS Newborn Blood Spot Screening programme, including isovaleric acidemia.

Even though dysosmia often goes away on its own over time, there are both medical and surgical treatments for dysosmia for patients that want immediate relief. Medical treatments include the use of topical nasal drops and oxymetazoline HCL, which give an upper nasal block so that the air flow can't reach the olfactory cleft. Other medications suggested include sedatives, anti-depressants, and anti-epileptic drugs. The medications may or may not work and for some patients, the side effects may not be tolerable. Most patients benefit from medical treatment but for some surgical treatment is required. Options include a bifrontal craniotomy and an excision of the olfactory epithelium, which cuts all of the fila olfactoria. According to some studies, transnasal endoscopic excision of the olfactory epithelium has been described as a safe and effective phantosmia treatment. The bifrontal craniotomy results in permanent anosmia and both surgeries are accompanied with the risks associated with general surgery.

Intake of carbohydrates which must be converted to G6P to be utilized (e.g., galactose and fructose) should be minimized. Although elemental formulas are available for infants, many foods contain fructose or galactose in the forms of sucrose or lactose. Adherence becomes a contentious treatment issue after infancy.