Report on Valtrex Side Effect and Usage by AskDocWeb

About Valtrex

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What is Valtrex?

Valtrex, pronounced VAL-trex, is the brand name of Valacyclovir hydrochloride. The valtrex pill for herpes, herpes zoster (the painful rash known as shingles) and herpes simplex (cold sores), is the same one used to treat chickenpox. It is also prescribed to suppress the sores caused by genital herpes. Valtrex is made by Glaxo Smith Kline.

How does Valtrex work?

Valtrex interferes with the activity of enzymes needed for reproduction to prevent the virus from multiplying.

What are the Side Effects?

The most frequently reported side effects are:

  • headache (up to 38%)
  • nausea (up to 15%)
  • abdominal or stomach pain (up to 11%)
  • painful menstrual periods (up to 8%)
  • depression (up to 7%)
  • vomiting (up to 6%)
  • joint pain (up to 6%)
  • increased liver enzymes (up to 4.1%)
  • dizziness (up to 4%)

Other side effects may include: agitation, allergic reactions, mania, muscle pain and menstrual problems. An uncommon side effect is hypersensitivity to sunlight called photosensitivity that results in a rash when skin is exposed to sunlight.

Some side effects of Valtrex may indicate a serious problem and should be reported immediately to your doctor. These include but are not limited to:

  • Aggressive behavior
  • Confusion
  • Decreased urination
  • Difficulty breathing or swallowing
  • Hallucinations
  • Hives
  • Itching
  • Seizures
  • Speech problems
  • Tremors
  • Unexplained blisters or peeling of the skin
  • Unexplained fever
  • Unexplained skin rash
  • Unexplained swelling
  • Unsteady or shaky movements
  • Unusual bleeding or bruising
  • Vision changes, including blurred or double vision
  • Wheezing

These symptoms may indicate a need for medical attention. Please do not delay in getting it.

The effects of Valtrex during pregnancy and breast feeding have not been adequately studied. If you are pregnant or plan to become pregnant, notify your doctor immediately. If you are nursing and need to use Valtrex, your doctor may advise you to discontinue breast feeding while using the medication.

Because rare side effects occur so infrequently it is difficult to tell whether they are caused by this medication or something else. Some of these rare side effects include but are not limited to:

  • Behavioral or mental changes
  • Diarrhea
  • Low blood counts:
    • white blood cells (neutropenia)
    • platelets (thrombocytopenia)
    • red blood cells (anemia)
  • High blood pressure (hypertension)
  • Hair loss (see Valtrex and Hair Loss)
  • Hepatitis (liver inflammation)
  • Increased heart rate (tachycardia)
  • Kidney failure
  • Vision changes

Neutropenia is one of the rare complications associated with the use of Valtrex. Neutropenia is a blood disorder characterized by a decreased number of white blood cells. This often results in a weakened immune system, making the patients more likely to acquire infection and creating a longer wound healing time.

If you miss a dose of Valtrex

If you miss a dose… Take it as soon as you remember. If it is almost time for your next dose, skip the one you missed and go back to your regular schedule. Allow not less than 8 hours between doses. Do not take 2 doses at the same time.

Conditions you should tell your Doctor about before taking Valtrex:

Patients with weak immune system, such as those with HIV infection or those who have under gone a bone marrow or kidney transplant may require a reduced dosage of Valtrex.

When taken by people with kidney disorders excessive doses of Valtrex have been known to cause psychological problems and kidney failure. If you suspect an overdose, check with your doctor immediately.

High doses of Valtrex have proved dangerous in people whose immune system is compromised because of HIV infection, bone marrow transplant, or kidney transplant.

Tell your doctor if you’re taking any of the following medicines:

Avoid Valtrex if you are sensitive to it or the similar drug acyclovir (Zovirax), drugs that may damage the kidneys such as Neomycin or Streptomycin, Valtrex can make your condition worse or affect your central nervous system.

If you are taking Valtrex with certain other drugs, the effect of either drug could be increased, decreased, or altered.

Check with your doctor before combining Valtrex with cimetidine (Tagamet) and/or probenecid (Benemid).

Storing Valtrex

Storage instructions: Store at room temperature, away from children.

General Notes

Because Valtrex may cause dizziness, do not drive or perform other hazardous tasks until you know how you react to this drug.

A small number of cases (less than 1%) of alopecia (hair loss) have been reported by users.

If you are taking Valtrex for shingles, you should start using it as soon as possible after your doctor has made a diagnosis. It’s best to see a doctor and start the drug within 48 hours of first noticing the rash. If you wait more than 72 hours after you first get a herpes zoster rash, the medication may not be effective.

If you are using Valtrex for genital herpes, begin taking it at the first sign of an attack. The medication may not be effective if you wait longer than 72 hours after the first attack or 24 hours after a later attack.

You may take Valtrex with or without food.

Valtrex relieves the symptoms of genital herpes, but it is not a cure. There’s also no evidence that it will prevent transmission of the disease. To avoid spreading the infection, don’t have sexual intercourse during a flare-up. Valtrex is not intended for use in children.

There are no known food interactions with Valtrex.

Valtrex has been used successfully to treat chronic-fatigue syndrome which affects about 6 out of every 100,000 people. Many of the patients who were infected by the Epstein-Barr virus regained cardiac function and returned to normal life after taking high doses of Valtrex. Talk to your doctor about this one before trying anything.

There are 8 human types of the herpes virus:

  • HSV-1 means cold sores and fever blisters
  • HSV-2 means genital sores, chicken pox and shingles
  • Epstein-Barr is a common cause of mononucleosis
  • Cytomegalovirus, which is serious when contracted during pregnancy
  • Herpes virus 6 or roseola is a type of measles
  • Herpes virus 7 causes a rash
  • Herpes virus 8 causes Kaposi’s sarcoma, an infection seen mostly in AIDS patients

Common Misspellings for Valtrex

Valtrex is often misspelled, as many people hear the word verbally, write it down and spell it incorrectly. Here are a few of the most common misspellings for Valtrex: Veltrax, Valtrax, Voltrax, Voltrex, Veltrex, and Valtracks.

Valtrex Feedback

If you’ve used Valtrex, please help others by sharing your experience with side effects. What would you tell your best friend about this product? Please remember that we do not give medical advice. That is for your local health care provider, who is familiar with your medical history. You can use the form below to add your comments, feedback or Valtrex review.

Subj: Valtrex
Are there any side affects from drinking alcohol while taking Valtrex?

AskDocWeb: Only the ones you get from drinking without the Valtrex.

Subj: Re: Question about Valtrex side effects

Can you please elaborate on the statement from your website: “Valtrex can make your condition worse or affect your central nervous system (brain and spinal cord)”. I have been taking this medication for over a year and it has caused my condition to become worse, however, it is significantly worse when I do not take any medication at all. I also have nerve spasms often during the night. Thank-you.

AskDocWeb: That’s from the section, “Tell Your Doctor if you’re taking any of the following medicines:” It has to do with the possible effects of combining Valtrex with drugs that may damage the kidneys such as Neomycin or Streptomycin. Tell your doctor if you are taking either of these drugs. This is of special concern for the elderly.

Subj: Valtrex

I am taking one Valtrex 500 milligrams per day for suppression purposes. Will this ruin my kidneys? Have you had any reports of anyone urinating frequently while on this medication? Are there any long term health risks with this medication? Thanks,


AskDocWeb: There are a few reports of frequent urination but that is not listed as a side effect.

Subj: Yeast imbalance

HI I recently began taking valtrex and I was wondering if one of the side effects of the drug could cause a yeast infection? I didn’t know if maybe the meds could make my yeast unbalanced? Thank you!


AskDocWeb: Yeast infections are not caused by antiviral drugs. However, it is common to get yeast infections the first year or so of getting herpes. After that they tend to taper off.

Subj: Valtrex

Hi. I have been taking Valtrex for over a year now, in the last six to eight months I have been taking two a day, 500 mg. I have noted a sharp increase in aggressive and hostile behavior when consuming alcohol. Is there a contraindication for alcohol and Valtrex combined? I am a 47-year-old female. I also have been experiencing abdominal pain, bloating, weight gain, and menstrual irregularities. Could these be side effects of Valtrex? I would be quite reassured if that were the case. Thank you


AskDocWeb: Although no interaction is listed for alcohol and Valtrex you may still want to avoid it. Alcohol lowers the strength of your immune system. A few people have reported an increased susceptibility to the affects of alcohol.

Subj: Valtrex
Date: 9/17/2003

Is pharyngitis a side effect of Valtrex? I took Valtrex for 7 days, 500 mg twice a day. Two days after the full course, I started having pharyngitis.

AskDocWeb: Pharyngitis was not found to be one of the side effects of valtrex.

Pharyngitis (sore throat or strep throat) is a common illness and may be caused by viral infection (90% of cases) or by bacterium (10% of cases).

Additional Notes:

The herpes virus can pass between partners even during foreplay, oral sex or use of sex toys. If you or your partner has a cold sore or blisters on the anus or genitals, consider avoiding sex until these clear up.

Using a condom to cover the blisters will give you some protection as long as you use it from the start of any skin to skin contact. Also, washing with soap and water after sex may also help decrease your chances of infection.

If you have a herpes infection, keep your hands, your partner and toys away from the blisters. You can spread the herpes to other parts of your body, including your eyes.

You can learn to notice the earliest signs of an infection (tingling or burning in the skin) and begin using medication immediately. This can shorten if not abort the attack.

Although it is not known what triggers an attack, you might learn to recognize what triggers an outbreak in your own body. Stress, immune compromise, sunburn and injury are all suspected to play a role. Avoiding these typical instigators might help prevent attacks.

The first sign of a herpes infection might be the same symptoms you’ve come to recognize from any viral illness: fatigue, fever, aches, and loss of appetite. Within a week, you begin to notice a burning pain in the skin at the site of infection, followed by a cluster of blisters a day or two later. The blisters are full of herpes virus making you highly contagious. Within three to five days the blisters rupture, leaving behind pink shallow ulcers that crust over and heal. It is extremely rare for these to scar unless you scratch the blisters and they get infected with bacteria. The entire cycle lasts about two weeks.

Subj: Terrible ordeal
Date: 10/29/2003

I just recently went through terrible ordeal. I was prescribed Valtrex for a chronic Shingles and Herpes II problem. I went on a regime of Valtrex 1 Gm tid for 2 weeks, just after an outbreak. Initially, I felt better, the outbreak took a long time to go away, but then resurfaced while on the medication. Just at the end of the 2 weeks, I began having terrible burning spinal pain, and then spinal stiffness. I had to go to the emergency room, and they proceeded to do a spinal tap, thinking I had meningitis. They performed every test imaginable on my spinal fluid, for Lymes, Herpes, West Nile, etc. I was extremely debilitated, with ataxic gait. I even had entire brain and spinal cord MRI’d, and had tests for heavy metals, etc. All tests came back negative, so my only thought is that I was having a side effect of the Valtrex. I read up on your site about Valtrex, and saw that it should not be taken in people with immune compromise. I do not have a severe immunity compromise, but do have an auto immune disorder…Hashimoto’s Thyroiditis. I was not taking any Cemetidine, but was taking Prvacid at the time. Could you provide any feedback that would help.?

Sincerely, Sheryl

AskDocWeb: Anyone else have an experience like this willing to share?

Subj: Recommend Valtrex for cold sores
Date: 2/11/2004
I was prescribed Valtrex 1 gram caplets to treat a nasty cold sore outbreak and I want to recommend it to anyone who suffers from them. It’s a one-day treatment…you take two right away then two more 12 hours later. I had little faith it would help since I had full blown cold sores by the time I made it to the doctor. But I took it anyway, about 30 hours after I noticed the first tinglings. Now, two days later, the two cold sores above my lip are quickly drying up. It usually takes at least a week for me to get to that point. And I don’t get the little ones that go away quickly…I get those huge sores that take over half your face and give you a throbbing headache, a low-grade fever and make your glands swell up. Doctor gave me refills so if I feel another one coming on, I can take Valtrex right away. It’s definitely worth trying if you get bad cold sores!


Subj: Alcohol with Valtrex
Date: 2/13/2004
How much alcohol can be consumed while taking Valtrex without it becoming a health concern?


AskDocWeb: That’s like asking, “How much alcohol can I safely drink?” – not the kind of question we can answer. There are far too many variables like your weight, height, how long ago you ate, how much you ate, what you ate, etc. Add these to “your personal tolerance for alcohol” and you may realize you need to talk to your doctor to decide something like this.

Subj: Alcohol and genital herpes
Date: 2/13/2004
Is drinking alcohol safe if you have genital herpes?


AskDocWeb: Assuming you are not pregnant and you are not taking any medication that alcohol would affect, it would seem to be safe up to the point where it affects your judgement about your behavior.

Subj: Valtrex for suppression purposes
Date: 3/8/2004
I just started taking Valtrex for suppression purposes. But I’ve noticed my menstrual cycle is coming late. I am already 3 days late. I was wondering if this is a common side effect of valtrex? Thanks,


Subj: Effect on birth control
Date: 3/17/2004
Does Valtrex have any effect on the birth control pill?


AskDocWeb: We found no reports of Valtrex effecting birth control pills.

Read more feedback about Valtrex.

Most recent post: March 23, 2017

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